As far as life advice goes, “be yourself” may be trite and endlessly mocked, but it’s got something to it.
Taken literally, it’s useless. But I think we can take it more like “don’t be afraid to display every bit of who you are to people”. Even your worst traits can provide good bonding material with others. And if other people don’t like the parts of you they see, then first of all you’re still being true to yourself (so have nothing to be ashamed of), and second of all they’ll likely just choose not to interact with you as much in the future.
This does assume that the people who don’t like the traits you have are usually the people you wouldn’t get along with anyways, but I think that’s a fair assumption. It also assumes you’re mostly looking for people at your level—peers, friends, dates, etc.—and not merely trying to impress higher-ups. It’s definitely tactical to hide your true self from certain kinds of people you’re trying to impress, but I think people often confuse impressing others with finding others they get along with well.
The more willing you are to open up about your foibles, the more human and real you seem to others. If you imagine your life as a story, this is what makes for good writing. It’s hard to empathize with characters who have everything handed to them and never have to go through any difficulties.
I think people (myself included) also often underestimate how understanding other people really are. There’s a bit of a spotlight effect where, because we feel the fullness of our own lives merely by living them, we tend to feel like we’re under more scrutiny from others than we really are. Not so—other people are focused on their own inner lives, not on picking apart yours. When people seem disinterested in you, it’s very often because of something going on in their life, not their perceptions of yours. (Of course, just knowing this doesn’t make it much easier to deal with, but at least there’s a chance to remind yourself that things are probably better than they might seem.)
Along with this, sparking controversy isn’t inherently bad. So long as you’re taking a stance you find truly valuable, there will be people who side with you (and people who don’t). You don’t have the time and resources to afford presenting neutrality on everything. Let your true expression of your beliefs filter out people for you, since those are typically the people who you wouldn’t have connected deeply with anyways. In the long term, you’ll be happier with that than with some fake filter that’s even slightly misaligned with how you really feel.
It’s a guarantee that you don’t agree with a single one of your friends on every issue. Despite that, you somehow manage to get along. People are good at detecting what’s fake, and if you’re faking your way to likability, you’re probably sacrificing both your self-esteem and your esteem in the eyes of others along the way.
On the flip side of this, I think we should be more prepared to forgive people for trying to present their true selves. Communication is hard, so maybe be ready to accept that sometimes people are good, but have difficulty presenting that goodness to the world. I’d much rather deal with someone genuinely trying to be genuine (and making themselves look bad), than someone trying to slip past my disingenuity filter (and making themselves look good).