There is little that is as vexing as a gun that doesn't work right.
I would like to point out that sweeping generalities about auto pistols covers a broader range of design variations than generalities about revolvers.
SO when I hear how reliable 9mm autos are, I think of my P.08 Luger, and snicker.
I am in the camp that says screws coming loose OCCASSIONALLY on a revolver is normal. Certain combinations of design and caliber seem more prone to this, but finding some screw slightly loose on a revolver is something that happens. It doesn't happen to every revolver, or to everyone who has revolvers, but it happens once in a while.
Screws that come loose regularly are another matter, and screws that come loose after the use of the proper Loctite mean that the problem is serious, and needs expert attention.
Your 9mm S&W having several screws come loose is a defective gun. It needs to go to S&W, and possibly more than once. Factories are people too, and sometimes need more than one "shot" at identifying and fixing what actually is the problem.
Finding two, three or more screws loose after firing a couple hundred rounds, every time you do it isn't normal, and isn't normal maint for revolvers.