> it's cached by every major CDN already

I’ve never found this to be true any time I’ve measured, especially for mobile clients. Small caches with lots of versions and CDNs really cut into the theoretical benefits.

I wish I could find it, but I read an article a while ago that showed how CDN-cached stuff usually, well, isn't. At the very least it's not something to rely on when making decisions about payload size.

It's cached at the CDN nodes, which means quick delivery to the device.

This is much better than serving that file from your origin server, and even if you use a CDN it's unlikely that it'll match the hit rates of the public CDNs. That can make a measurable improvement, and at worse is no slower than hosting it yourself.

Have you benchmarked that? Each host you add has its own overhead thanks to DNS, TLS, etc. and every time I’ve done the tests, that cancels out the benefits entirely for a site which itself uses a CDN. I’ve also tended to see numbers for public CDNs which suggest that things aren’t cached as often as you’d like - maybe if it’s a popular project which hasn’t updated in years but otherwise version spread undercuts hit rates dramatically.

My rule of thumb is that public CDNs aren’t a performance move in the HTTP/2 era (i.e. 2016 or later). They may still be convenient, however.

Safari shards their cache by first party domain, so you don't get that caching benefit there.

Didn't know that. Looks like Safari is continuing it's devolution into becoming the next IE.

Advertisers have abused every single factor possible for tracking, including ETAGs and many other aspects of cache. Don't blame Safari for protecting it's users from disingenuous and dodgy tracking.

A single stable identifier would've solved the whole situation and Apple already had it with Advertising ID. Exposing that to the browser would've been enough so Safari could've been ahead of the curve.

Yeah, all you need to do is include a persistent identifier shared across all sites in the world! In fact, this solution is so great you don’t even need cookies anymore and you never get logged out if you accidentally delete them!

Is this sarcasm? The Advertising ID system is from Apple and in use in all apps, and it can be reset at anytime. It increases privacy, security, and efficiency.

Yeah, it’s efficient alright. Therefore the advertising ID is only accessible to apps that have declared their interest and these have to meet specific requirements. Not just any random website.

I don’t care what you or your industry today decides it ’needs’, you’re not getting a persistent webwide tracking ID.

"Solved the whole situation"? From what perpective? Completely killing privacy is not a solution, quite the opposite.

Advertising ID is Apple's own standard and already in use. It's what mobile apps use but it's the most privacy conscious method since it has no personal details and can be reset at anytime.

Making that available for apps and websites would've eliminated 99% of cookies and user syncing pixels since the industry could use a short-term stable ID to track engagement and conversions.

> since it has no personal details

Unfortunately the industry doesn't work like that, the name of the game is "collect everything and anything at any cost".

It is so bad that there is barely any difference between the behavior of "legal/legit" players (established advertisement businesses like Google) and scammers, Google for example bypassed 3rd party cookie restrictions on Safari, just like sophisticated scammers use any means to collection information on their targets for social engineering.

What this means is that not only there is no reason to believe that advertisers will be happy with a short-term stable ID akin to Apple's Advertising ID, they have time and time proven to go above and beyond to track users by any and every mean possible.

So what introducing something like Apple's Advertising ID to web will do is merely add yet another identifier to endless bucket of targeting methods already in use, sadly, it won't make advertisers stop abusing other things like cache so we can have nice things.

That's exactly how the industry works. I've spent more than a decade in it. We're talking about IDs, not tracking other information.

IDs are needed for 2 primary reasons: controlling ad frequency and attributing clicks and conversions to an ad impression.

Cookies worked for a long time but they were always considered loose short-term and anonymous identifiers. Apple had a opportunity to offer a better device-level option that had the same privacy but much better efficiency, and yet decided to break APIs and user experience instead, while also entrenching the big companies at the detriment of everyone else.

It's a privacy thing. I expect we'll see Firefox and Chrome sharding cache as well.