This.

It's a choice.

I almost never use web apps; I do only when what I'm doing is fundamentally a web interaction: banking, for instance. Everything's on their servers anyway.

For everything else, I (too) use shell applications. Even if I didn't, there are tons of native GUI applications to choose from, and they are often far better experiences than SPAs or Electron apps: just look at the memory and CPU use, if you want a baseline metric.

Why do people do this? Because they fancy that they're providing a good enough interface that works on every OS. Which is often not the case, and by the time you invest enough effort to get your SPA working well on every possible platform you could have written native apps that look and function better; and most organizations still throw in the towel and add a caveat "works best in X", giving lie to the "web apps work everywhere." So: laziness, or being cheap, and not really carrying about the user experience: those are the reasons people write web apps.