personally I always thought that the other aspect of that is that while you shouldn't change for anyone except yourself, if you don't wanna change don't expect your results to change either
if what you're doing isn't working for you it's time for a change but don't completely abandon any and all of your principles (I saw a meme of a black guy posing with a confederate flag surrounded by white girls lmao)
Yeah, I tend to think of making changes to benefit yourself as being in the self improvement category. Really, anyone who isn't in a constant state of change is stagnating.
But like you say, if you make changes that are against your principles just to please other people, or women - that's supplicating behavior. Now it may be that your principles need to be re-examined, and that's okay too. As long as it's authentic to yourself.
An example for me: I had a friend from high school, he did pretty well with the ladies. But he always lied to them, made up ridiculous lies to make himself look impressive. A lot of guys do that, and if it works for you and you don't care, great. But I have no interest in representing myself as something other than what I am in order to impress someone. Not my style. Funny thing is, my friend was hard working, charismatic, and was considered to be quite good looking by females. He didn't need to lie to them to impress them, and I don't think half of them believed him anyway.