I haven't used desktop Linux recently, but my expectation would be that e.g. gnome is a little better than Windows and macOS, but still not great compared to what we had 20 years ago.
So there's just something broadly bloated about modern software. And, sure, people largely don't notice because modern hardware is so damn fast, but we're also forcing users to buy hardware that is much faster than what they should need.
GP points out that faster CPUs allow us to do things that weren't possible in the old days, like real-time video transcoding, and I agree that's great! But if you just need to check your damn email, you should be able to save a great deal of money with a machine that's laughably underpowered by "modern" standards, while still checking your email at the speed of light.
What is all this software doing? I guess we're e.g. rendering at higher resolutions than we used to, but isn't the GPU supposed to take care of that?