This is what I see online, but this hasn't been my experience for any of my devices. My current phone is on year 5 with the same battery, and it's still very decent. I charge it every day to 100% and often plug it back in while it's still at 50%, so it's not like I'm being more careful than usual.
There's a cynical part of me that thinks that these kinds of numbers are put forward by the industry to feed the narrative that these gadgets need to be replaced regularly.
I had an iPhone 6s that I used for about 5-6 years before upgrading and giving it to a friend to use. I replaced its battery at about the 4 year mark, and as far as I know it’s still going strong. I wanted to upgrade it earlier than that, and I could afford to - but why bother when my phone already did everything I needed it to do?
3 years of security updates is a joke. The hardware easily lasts over a decade if you want it to.
When I bought the phone the battery was one downside I thought about but thought "it will probably be OK". I was wrong ^^ And due to its aluminum unibody construction you must remove the display to replace the battery, nothing I would want to risk on my daily driver device.
But if you think about it, it doesn't even work here. First of all, no one can tell you that your battery has a poor capacity, because you test it daily. And people are pretty sensitive to this issue, because we have tricked the manufacturers to create phones that have just enough capacity. (By requiring faster phones, larger, better screens and thinner phones. And not requiring a battery that lasts much more than a day.)
Actually that 'narrative' has the opposite effect: there are a lot of articles online that tell you how to enhance the life of the batteries. (Whether it's really needed or not doesn't make a difference.)
Regarding charging it from 50%: this is not something that hurts Li batteries. Actually it's better than allowing it to drain (or go into some unspecified low percentages, probably below 20 or 10). Charging to 100% is said to have a negative effect. I mean it probably wears faster than if you charge to just 85%.
Like Samsung Battery Protection? It limits charging to 85%. I would personally have used the 80% threshold, but after 2+ years of heavy use, the battery has held up quite well on this Note 20.
Speaking about batteries, what would be nice if they added a setting that allows defining charging limits, e.g. like what we have on Lenovo Thinkpads. (You can specify both the upper threshold and also the lower one, so that charging doesn't start if the battery is above that level even if you connect the device. Which you may do to a phone even without wanting to charge, e.g. if you use it as a modem.)