The same would have been true if your first phones were Android and your most recent ones were iPhone. In other words, your experience has nothing to do with A

The same would have been true if your first phones were Android and your most recent ones were iPhone. In other words, your experience has nothing to do with Android vs iPhone, rather that earlier devices simply didn't have the same amount of resource headroom as more recent ones. Ever since the iPhone 4S, they've been usable for at least 3 years before expectations catch up to them. And now I think since the 6S and SE—which have the same hardware generation—iPhones can claim to have 4+ year lifetimes. (At 3.5 years old, the iPhone 6 is still a great device today, particularly with a cheap battery replacement.)