One problem with calling one's self a rationalist is that there is no barrier to entry for others. You're identifying with a group that anyone can claim to be a part of, and it shows. (In comparison, "Effective Altruism" has at least the notional requirement to tithe.)
But self-IDed EAs can be checked against objective reality in exactly that way - there is no obvious equivalent for rationalists. (Hmmm. I'd start with proving Bayes' Theorem, and asking for a list of incorrect predictions and when they changed their mind about something major.)