In my past job, we couldn't be bothered with all these big tech politics, so we actually disabled all the third party signups. We would require phone numbers because our value proposition was validating that users were real and easier to ban. Apple was not happy with this and their Apple sign ups allowed more anonymity, just a pain overall. We couldn't enable the others on Android either, because they'd be able to sign up with FB on a Samsung then can't do it on an iPhone, and that was just messy.
