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.
Edit: I mean, I do get it, I just don't like it.
That said, I've had a burner email for as long as my personal email for this very reason. I even have 2 burner gmails. It's not exactly a huge invasive measure like a phone number (which I'd never give to a site that isn't trying to take payments. Hell, still haven't given Amazon my phone number).