I was invited same way.

But it turned out OK. I got FC buffs, new chat, some people that can help me that I can help. Inactive people are dismissed, new are invited. So FC population is filtered that way.

This method is not acceptable for so-called Hardcore FC-s, but it is fine for casual or social FC-s without that high-end goals (though there are indeed maybe problems with high-end goals for members in there).