One thing to call out is that this is true for consumer created Meet calls, but not for G Suite/Workspace created Meet calls. Users w/o a Google account can join those calls by “knocking” and being accepted to the call (by the organizer or a user on the same domain) [1]. There's also a dial-in by phone option.

[1] https://support.google.com/a/answer/7582940#top&privacy&encr...

[Edit to clarify wording and add citation to Workspace specific HC article]