Problem is, the actual work we used to do locally and now do over webapps has to pay the performance price of browsing the web - resulting in severe UX degradation for anything but the most casual of uses.
It's partially modern web frameworks, too. I happened to load up the web version of Slack on a Core 2 Duo running at 2.2 GHz today, and it was unusable. By comparison, I remember using AIM via Meebo (remember that site?) on dial-up back in the late 2000's, on a Pentium 166 MHz laptop. It wasn't exactly snappy, but it was better than Slack was today on a 2 GHz laptop with 500 times the bandwidth and a fraction of the latency.
It probably would have been even better if I'd been using a native AIM client instead of Meebo, but I'm amazed by how inefficient some modern websites are.
Quite right; the vast majority of "actual work" that one would do locally on the machine, requires a lot less power than booting up a web browser and surfing to a random "modern" website. Funny how that works.
We're all forgetting about the 'real' work that we routinely do on our computers, because that kind of thing has gotten so rock-solid and doesn't even measurably tax compute resources - even as browsing the web, of all things, has only become increasingly fiddly and heavy on our systems.