Not sure what you mean by "diverse". There is a lot of legit macOS software, which is 32 bit only and no longer updated - for example because the company went out of business or couldn't justify the effort for a port. Cutting support off for these programs is a harsh step. While I can understand that Apple doesn't want infinite backwards compatibility, it hits a lot of users. One reason for this might be the preparation for the bigger switch to a new cpu architecture.
The best bet is Windows since it would happily run software made 25 years ago in Windows 95 time.
To use macOS, you have to be satisfied by using the apps which run on macOS: Adobe apps, Apple apps, Microsoft Word and open source software.