Google leverages their monopoly search position to push people towards Chrome, using messages that, to lay people, imply a lot of websites won't work correctly unless they install Chrome. This is the most charitable reading, assuming they don't deliberately impede compatibility with third party browsers.
You used to be able to do this, but e-mail has been required for some time.
Over on Lemmy, it is the instance operator's choice whether or not to require e-mail, but most instances currently do as a measure to mitigate bot signups.