source?
Rate limits: https://superuser.com/questions/1453258/what-could-cause-429...
Take your pick of lockout horror stories:
https://twitter.com/Demilogic/status/1358661842147692549
https://twitter.com/raveofravendale/status/13895079282693939...
Edit: Also don't forget their Maps API change that sent many developers to the wall https://imgur.com/gallery/ZuWMooq
I think the rate limit user was simply not sending the API key correctly or having some very poor code, you get 100 request for 100 seconds for each user, you just need to use the token of the user not yours. As for the horror stories that's with everything you could argue that Stripe is a horrible idea because Visa could block them, but I do see your idea here, I'm planning to add some "spreadsheet features" directly in the app to avoid being completely dependent on them
When they start rate limiting and banning your users they'll be the ones demanding refunds from you.
On top of that users would need to commit their data to Google's ownership and if they're using the free versions of Sheets good luck if their account gets locked because the algorithm demands it to be so.