I can't speak on behalf of him, but all my old CD-ROM games from the late 90's and early 2000s don't work on Linux, even with Wine. I'd love to get them working one day, so I'm watching this thread

Primarily Solidworks, Fusion360, Altium, and Traktor Pro. Planning to start learning about video editing soon. Also games, though I'm planning to try Bazzite soon.

Not him, but I almost never boot windows, but the other day I had to change a part of a a stupid powerpoint presentation that only could be done using Powerpoint desktop app. Wine has not done so well with it, Libreoffice wouldn't do the thing right, and browser based office can't touch 'master slide' content.

For me it's Adobe. Stupid government and other forms I need for work. No available third party software will work on some of them, and I've tried them all. And for some dumb reason even having an Acrobat subscription won't let me fill them out on their (extremely buggy, by the way) web app.

Was never able to get it working with wine.

That, and the compatibility between Libreoffice (or other Linux office software) and MS Word is still terrible. I'm quite sure that's mostly due to shenanigans by MS. So if you have to swap documents back and forth between people (e.g. with track changes) it just doesn't work as well. And, like Adobe, the web app version of Word seems to be kneecapped in a few key places.