And no, I don't want to hear about the software XYZ that is almost just like any of the above, because they aren't even close.
If I just wanted to browse the web, and work in a terminal, then linux is great.
How many distros would they need to support to make customers happy? At what point does it become a problem of diminishing returns?
Windows and macOS are pretty big. How many more customers would Adobe get by adding support for: Ubuntu, Fedora, SUSE, Mint, Arch, Manjaro, MX, Gentoo, Elementary, and so forth? At some point it just gets silly and devolves into Muppet names and other nonsense -- and each one has a smaller amount of users.
Plus, real professionals are willing to pay for software. Open source is frankly not relevant for professional image editing, video editing, music production, CAD, etc.
Or edit video, or make music, or write all the stuff that makes this possible.