Maybe? It doesn't square with my personal experience, at least. I went through the usual spiel with someone last night, without knowing whether that was going to be a deal breaker, and I very easily could have avoided that problem, because (1) I'm a good liar, or at least I was back when I let myself do it, and (2) this person and my SO live in totally different cities and run in completely different social circles, so an alternate version of me who's willing to cheat and lie would have no reason to think that keeping this particular secret would be hard to do.
On the other hand, my father lied a lot and much of who I am today is basically An Attempt At Being Not-Him, so I might have a Weird Reluctance To Lie for reasons other than "am a nerd."
Blindsight, by Peter Watts, helped a lot with my depression (though I am very much an outlier here, and nobody should expect the same result) and was sort of my "rabbithole" moment for thinking about brains and consciousness and "What makes me, 'me'?" and so on, which continues to pay dividends insofar as a hugely useful tactic for dealing with depression is realizing that "you" are, at best, just one brain-part of a whole system of brain-parts, some of which are malfunctioning, and that e.g. you shouldn't necessarily trust the brain-part which is saying "You are awful and need to die."
(It also helped my depression because there's just a certain element of "horrifying beauty" in Blindsight, but again I don't expect other people to agree.)
Re #2 I have bipolar, and it would be very easy to just give up on a lot of pursuits or decide that I wasn't getting anywhere with them. In particular, I often feel bad about my writing, but the records that I keep (inspired in large part by rationalism, but also partly by my time as a cult recruiter, where there was a focus on tracking various "key indicators") are able to demonstrate to me that I'm doing better than I usually think.
The emphasis on taking "The Outside View" is also immensely helpful. Ten years ago, I wanted to publish novels, and I still haven't finished a novel, let alone published one, but I've done a lot of other stuff that wasn't in the original game plan (e.g. maintained a good GPA throughout grad school, run several successful Kickstarters, published a line of nonfiction resource booklets) and, if I were talking to someone with those accomplishments then I'd say they had done well, so I have to say the same of myself.
Re #3, I'm a socialist, and without rationalism it'd be very easy for me to slip into black-and-white "my side is always right and the other guys never have anything worth paying attention to." Instead, I'm more critical of everyone (even if I'm probably not quite as critical of My Guys as I think I am, because that's how humans work) and I'm more willing to change my views (I have, for example, shifted significantly away from anarchism). Likewise,
Also, another one, because I was in a rush last time: Rationalism helped me figure out how to bring my migraines down from "incredibly debilitating for an entire day, and sometimes two days" to "mildly debilitating for part of one day and sometimes just mildly annoying", because it gave me a more "If I have a problem, let's experiment with possible solutions and be very careful about keeping track of the result of each possible solution" mindset. Not only have I found some great ways to deal with my migraines (and I know that they're responsible, because every now and then I fail to do things properly and then my migraine is around as bad as it was before I started doing whatever it is I failed to do) but I was able to stop doing some things which folks felt worked for them but, as it turned out, were useless for me.
1. Helped me to get out of a cult.
2. Given me the mindset that any negative aspect of my life is (probably) fixable if I can just find the right angle to approach it from.
3. Kept me from falling into all kinds of political weirdness, and reminded me that My Guys shouldn't exist as such--I might have certain political positions which are shared by certain other people, but if I start thinking in terms of teams then I'm going to fall down a very bad hole.
In support of your argument: I only looked up "Ally McBeal" a few minutes ago, and promptly discovered that I not only lacked all but the most cursory information on Ally McBeal but that what information I did have was almost entirely wrong. The name of the program was not "The Ally McBeal Show," it was not a talk show or comedy sketch show or anything similar, and Ally McBeal is a wholly fictional character, rather than the name of a living person and that person's fictionalized persona à la Ray Romano of Everybody Loves Raymond.
I think it would be fair to say that I previously had "no idea who Ally McBeal was." Despite knowing that the name pointed to something, I was incorrect in just about every respect except for which pronouns to use and it had something to do with a television show.