They made the users suffer for their unwillingness to cope with their situation.
Instead of planning ahead and only accepting a limited amount of users, which would have severed only a fraction of users from us, they decided to grow to become one of the biggest instances, and now took some interesting communities with them, along with cutting off their own users from communities here.
I hope their user base migrates to other, more open instances, and the communities lost will spring into existence elsewhere.