As a product owner, because what if that service provider decides to (mis-?)interpret something you did as against their TOS and revoke your access to their sdk

As a product owner, because what if that service provider decides to (mis-?)interpret something you did as against their TOS and revoke your access to their sdk, thereby making it more difficult for many of your users to log in? And as a user, what if Facebook/Google/Twitter/Apple decides you've violated their ToS, blocks you from your account, and now you can no longer log into any of the sites you've linked with one of those providers? I know this is a bit extreme, and for many people, the risk is totally worth the reward, but I think that is one of the chief concerns many people have with trusting a third party for all their sign-ins. It's a single point of failure.