If you did your job right, you have people that are much more experienced than yourself. The only smart move is to coordinate them and, at best, give your opinion.
I don't really google "what's the best suturing technique" and demand my doctor to follow those exact instructions.
"You hired me as your UX expert. I use A/B trials, prior trials, studies, and knowledge I've pieced together over the past 20 years." The question of "What are you even paying me for if you're going to ignore my advice?" is one I'd love to ask but fear getting fired for pointing it out.
The alternative to micro-managing is asking for the impossible [0]. Which also happens frequently. I was once asked to make a transparent .jpg because .png are "too heavy". I had to explain how .jpg's work, tell them I could make it a .gif, but that the .png compressed better and would be more lightweight than the .gif. They insisted on the .jpg at which point I gave up, matched the jpg's background color to the blue background they had and saved it as a .jpg. Which turned out to still be a bigger file size than the equivalent .png.
Or even just rename to foo.jpg and figure the MIME type and file header would be enough for browsers to still render it like a PNG.
I wish people felt this way about economics, instead of constantly voicing their "market solves everything, government is bad" opinions and trying to apply econ101 solutions to complex problems.
My approach is to hold myself from telling the designers what to do, and instead tell them what the problem is and let them come up with a solution.
I agree with your second point. Still, there's a very thin line between "telling them what the problem is" and burning out your best employees.
I guess experience and empathy do help us get such balance.