All the 4 & 5 star hotels I’ve visited have had very good hairdryers usually kept in a drawer by a dressing table. I can’t remember when our where I last saw a wall mounted one. Even my last Emirates flight had a dryer in the amenities drawer.
Having said that I’ve never in my life used a hairdryer to dry my hair. For me the biggest use is when I have a stain on my shirt after lunch and I wash it out, I can then quickly dry it with the hairdryer.