In theory, the name is supposed to imply that they're pursuing rational thinking and philosophies, not that their decisions are the rational choice.

That said, I was surrounded by rationalists in my younger years by pure coincidence and spent some time following the blog links they sent and later reading the occasional LessWrong thread or SSC comment section that they were discussing each day in chat.

It's pretty easy to see that the movement attracts a lot of people who have made up their minds but use rationalisim as a way to build a scaffold underneath their pre-determined beliefs in a way that sounds correct. The blogs and forums celebrate writing of a certain style that feels correct and truthy. Anyone who learns how to write in that style can get their ideas accepted as fact in rationalist communities by writing that way. You can find examples throughout history where even the heroes of the rationalist movement have written illogical things, but they've done it in the correct way that makes it appear to be "first principals" thinking with a "steelmanning" of the other side along with appropriate prose to sound correct to rationalists.