The reason for this is simple enough. The proprietary software has an agenda to squeeze as much from the user as possible, and the Internet has enabled this to horrible degrees.
Windows is about making the least effort to be the de facto OS while slamming you with ads and insistence that you must subscribe to various Microsoft services.
Applications that make zero sense to be browser hosted are browser hosted, because it means to have to be approved by the vendor every time you run the software, it must be subscription.
Transactional software purchases are garbage for the business side of software, there's a mandate for recurring subscription based revenue.
It used to be these opportunities were impractical and the commercial company budget would sometimes lead them to an easier product than open source, but that ship sailed.
Now for technical users, open source almost always has won and will continue to win, because they are dealing with like minded developers writing for themselves, and so they internalize the use case in a way a commercial approach never can.