There’s a very good reasons why people and organisations will pay for proprietary software when there is a free alternative available. I’ve used FOSS word processors before, for example, and they’re okay, but nothing like what Microsoft Office can do. Same with video editing.
I think creatives on Facebook overestimate their value to an extent, I use Facebook to see what my friends and family are doing, and because the sports I do are mostly arranged through Facebook pages.
The webcomics etc I follow are cool, but if they stopped posting I wouldn’t really miss them all that much.