I bought a replacement in 2015 (months after the problem started), so no, I wasn’t trying to use the latest iOS on a 5 years old phone. Even if I was, it’s up to them to make sure it runs at least well enough and/or to provide a way to downgrade (something that Apple didn’t [still doesn’t?] allow you to do) as customers have no idea if the update has a problem before they install it and use it for a while.

Only Apple can prove this as all we have is rumours, but I believe they started playing with the idea of slowing down devices way before that wider release years later. I remember finding similar reports when I tried to find out what was happening to my phone. There were complaints even on Apple’s own community forums: some owners had laggy iPhones while other owners, with the same device/model, were fine. Unfortunately, other than the usual user blaming from people that didn’t have the problem and the “buy a new phone” comments, no one suggested an actual fix.

The slow down in 2017 was huge for some people. Here’s a 3 year old iPhone 6 that had its frequencies go from 1400 MHz to 600 MHz: https://twitter.com/Sam_RMSI/status/943400254451335168

I’m far from being an Apple hater - I’m typing this on a M1 MBP after all - but it’s not okay to slow down phones like that without any warning, information or a way to disable the “feature”. The person above had their clock speeds drop to less than half of the original speeds! Like, what the heck?

I’m sure they had good intentions, but in practice they slowed down some devices too much without any warning or a way to reverse the change. All their fixes for the problem they created involved giving them money: you either had to buy a new phone or pay for a battery replacement which was not that cheap. They had to be sued first and only then they added a setting to disable the throttling and started offering affordable battery replacements…

This type of behaviour from companies shouldn’t be defended or praised.