This is true, I hate that this is true, and I hate that there's very little to be done about it.
I use Firefox for ideological reasons, and last week got off my ass and ensured all my documents (from Dropbox), music (from Google Music / now the inferior YT Music) and photos (from Google Photos) were stored in a way I could control. My plan going forward is to use an old laptop running Syncthing as my primary source of truth for files. Email is next (but more complicated since I don't want to self-host it).
It helps me personally to take Stallmanesque approaches to managing my digital life. And if Google continues to get more and more restrictive I have the technical acumen to find or make alternatives—or figure out how to do without. But I'm worried about the growing number of non-technical users who are increasingly dependent on technology and—startlingly—increasingly less technical. People who only use Google Docs on their phone and a laptop have no reason to understand that documents correspond to files on disk that can be edited by programs running locally.
It more and more seems like the future is tech oligopoly with more and more subscription fees. What else could happen once a generation has been trained to only use Approved Tools running on Approved Servers?