Yeah I have read such also, and indeed also for me it is not ideal to wear for long time, but it is still definitely significantly better than having to be listening to a laptop fan or similar. Listening to music with it I feel is better than just using it for noise cancelling, but I cannot be certain it makes a difference. Otherwise, if I do not have such mechanical noises around, I disable noise cancelling.
I'm conflicted on this one. I have really good Sony ones, and whenever I wear them for even 30 minutes, when I take them off I feel worse.
I don't know if it's all in my head and they objectively don't make it worse, however I also now avoid wearing them.
I've probably used them for < 20 hours in the last year, half of that while driving long distance. My car also creates a lot of white noise.
Different tyres will change the noise of a car too.
When I bought my last car, it came with a mishmash of different brands of cheap crappy tyres. They were quite noisy all the time, but when you hit exactly 80km/h there was some kind of resonating drone as well, that was very weird...
When I replaced them with good, high-end softer tyres, the noise was reduced by a massive amount all the time, and no more drone.