That's true. Pure Land buddhism is quite crazy if you look at the basic writings in buddhism. And you're correct in that buddhism can't protect its trademark as it were, like Catholicism can. But on the other hand, Chrisianity or Islam also can't, with funny situations like Unitarian Universalists who are, as far as I can tell, basically not christian in any meaningful way. Or in the case of Islam you get everyone saying everyone else is a heretic and people trying to kill each other.

In this respect, the Catholic Church got it right with the concept of excommunication.