The trickle in invitation system with which they made it public was such a glaringly obvious mistake it still makes me mad. So many people I knew had accounts there but stopped using it because their friends weren't there or by the time they could join their friends had already left because in turn their friends weren't there.

That, on top of branding it with the same name as the hated login system that[1] hamfistedly joined peoples accounts across vwry different contexts.

[1]: or so I heard, I wasn't affected, I postponed that part again and again until that part ended up being very smooth for me