You're not wrong. But, I recently did the mistake of upgrading my iPad to version 26 (the liquid glass version). I had a relatively smooth experience on my 6 year old tablet which now runs painfully slowly. Even scrolling through different parts of home-screen lags.

My point being, with time performance might go up. But instead of that making my device faster/long-lasting, developers use that extra performance to cram in more stuff, at the end of which I come out only slightly better if not worse (as is in my case)