While office can run in the browser, the browser version sucks and I commonly need to open the files in the desktop version. This often happens when there's a browser version or a mobile version or an app version. There's a lack of feature parity.

The browser versions aren't as good as the desktop versions. And Googles alternatives aren't as good as Microsofts. Both do 60% of the job, which is probably enough for 80% of the people.

The browser versions (and the mobile versions) are nowhere near parity with the desktop Windows version, even in quite basic matters of styling. To be honest this annoyed me enough in the end that I just moved to a PandaDoc/CSS/PDF workflow and honestly I now have both a simpler editing process, and a more powerful engine for customisation.

I don't think you'll ever see a web version of Visual Studio.

Only limited versions, and the usability downgrade is severe.