Granted, my big example of this is quite old (the iPhone 4 would run iOS 6 really well, while on iOS 7 it was a glitchy, slow, battery-draining mess) but it does seem to be a common trend (my last Apple phone, the iPhone 5 ran quite well on iOS 9 but would just have a complete breakdown if you installed iOS 10).
They were IIRC also caught red-handed a couple times deliberately releasing updates to older iDevices that would just wreck their battery life and have a few lawsuits pending about that.
Are you going to just drop an inflammatory statement like that and not even try to provide any information to back it up?
https://www.npr.org/2020/11/18/936268845/apple-agrees-to-pay...
Pretty much from the first iPhone model it's well known that newer iOS releases will slow down your phone and/or make your battery drain faster. I even remember when they actually broke wifi on a lot of phones with an update and pretended that the hardware was defective all the time (which it wasn't). Hell I'm looking right now my old iPhone 8 which got a new genuine battery, and it's a lagging, hot mess so I only use it when I don't want to burn the battery of my new phone.
My good colleague resisted updating her iPhone 11 to any newer version of iOS from the one she got, but couple of months ago she couldn't install her banking app anymore so she broke down and updated the OS. Instant laggines, and battery lost close to 40%. Just like that. She got mad, and when the madness subsided, she bought a new iPhone. Mission accomplished for Apple.
All of this could be much avoided if they would allow you to install previous versions of iOS, but they don't for obvious reasons. And before anyone mentions security, that is a load of BS because even previous iOS versions get patched up. So planned or premature obsolesence, the user just gets frustrated with an old phone which hardware-wise might be perfectly fine, but software-wise an unusable mess and buys a new phone. I hope the forced user battery replacement works, and I'm sure they could look into these forced software updates which are also largerly contributing to larger problem at hand.
Honestly, "it's well known" is anecdotal at best. If you're actually saying it was a problem that battery life dropped 40% from going from one update to another, then media would pick up on this. That's not a small amount here, you're saying battery is now 2/3 the previous runtime. If that was actually reliable and measurable, show me an article that has done testing on before-and-after from one update to another.
In your second paragraph you completely dismiss my experience I guess because it wasn't published by some online zine which is ridiculous by itself. Online forums like reddit are full of these, my experience says the same, and pretty much the big majority of my friends have iPhones in this neck of woods and there is no question on whats going on. Why there are no articles about it? Dunno, maybe because by now its an old story as this is going on for decades now so it's an accepted fact. Maybe because in US people buy iPhones more often then in Europe so the effect isn't that noticeable? I don't know, and it's not in my interest to care.
So I'll put my claim into negative and ask you this: are you claiming that iPhones are not slowed down by newer updates? Are you claiming that perfectly good iPhones even as new as 1.5 years and older are as performant as the lastest gen iPhones with the same iOS (even with brand new batteries)? If so, thats an extraordinary claim and the burden of proof rests on your shoulders.
Are you also claiming that you're casually able to install previous versions of iOS so you could get performance back? If car industry did the same after software updates whole industries would collapse. Does your PC even do this nowadays? If you install an OS which actually slows down your computer, you can still re-install a previous version to get your performance back. Not so on the iPhone, you're locked out of that option and we'll screw you, buy a new one.
The design of the battery in the 6 turned out to be problematic once the battery reached a certain age. After lots of reports of iPhones shutting down suddenly, Apple issued a software update that slowed down those phones so that they didn’t shut down. They then redesigned the battery and this was not a problem in later models.
You talk about a general slow down of phones when the OS is updated. That is most likely due to increased processing needed in later OSs. The early phone CPUs had barely enough processing to do what they needed to do so the added demands of a new OS would drag them down a little. Over time the cumulative effect would add up. This is not unique to iPhones. I have heard the same complaints from Android users. Fortunately modern phone CPUs are powerful enough that they have the cycles to spare and slowdowns are rare.
My understanding is that apps use more RAM now because newer phones have more RAM. The result is that older phones with less RAM will aggressively kill apps because there just isn’t enough memory to go around.
As a developer I can see both sides of the coin. On one hand, I know it would be possible to reduce the memory consumption. On the other hand, I realise this would also cost more money. But it isn’t malice. Just a choice.
Apple as a manufacturer have gotten a lot better over the years. I remember when iOS updates made the iPhone 3G literally unusable, but that isn’t the case any more. I’m running iOS 16 on my iPhone XS with no performance issues at all. I expect iOS 17 to be just as fast. They also implement features to increase the longevity of their phones, like reducing performance and maximum power delivery when the battery is degraded. They were lamented for this feature but it genuinely saved my iPhone 6S which kept on shutting off.
Rather the opposite: they don't try to keep your old phone working. The devs probably have the latest phone, and write code that works well with them. This code can be inefficient, as long as it works well on the newer phone, even if it makes older phones slower.
Maybe I am being pedantic, but I think it is different: it is _not_ that manufacturers actively pay their devs to make the phones slower (which would be planned obsolescence), but rather they _do not pay_ the devs to make sure the old phones _do not get slower_. The latter is "passive", that's (to me) premature obsolescence: the manufacturer could fight premature obsolescence, but it has a cost (and obviously they don't want to pay for it).