Not at all. In the early 1990s 9mm Subsonic was even considered the hot 9mm defense and law enforcement round. That thinking has changed a bit, but the 9mm subsonic rounds are still made, and bought up by civilian shooters as well as police and military for practice and defense.
Of course, the idea of a subsonic bullet being better for use in suppressed or "silenced" weapons goes back many years. The gas from the shot is muffled but if the bullet is supersonic there will still be a sonic crack from the round, a mini sonic boom if you will.
The venerable .45 ACP round showed a bullet can be subsonic and still deadly. It is still plenty fast, moving just under the speed of sound, and has plenty of mass. The standard 9mm is often supersonic, so loading a heavier bullet with less velocity is seen as a compromise, getting it subsonic for use with suppressed weapons while still having lethality. Standard 9mm is 115 to 124 grains, at least in NATO loadings. 9mm Subsonic usually ran at 147 grains if I am not mistaken.
I am sure other calibers can be made subsonic too, some more feasibly than others.
Shoot safe out there!
By the way there has been an "Ear safety" drive of sorts to get suppressors and silencers made easier to get in the USA but it hasn't really taken off over here. Most people over here see them and think of Spy movies. In Europe they are considered polite in some places, less noise from firing ranges and all. Interesting world we live in, neh?
Addendum on the 9mm, the ".45 like" blend of higher weight and slower speed in the 9mm Subsonic round had some early 1990s pistoleros thinking it would have more stopping power as a result, but, well, the thinking is drifting back another direction. Of course any factory 9mm round will work mostly due to how well the shooter places the bullet. Ah if only we spent as much time actually practicing as debating, nitpicking and arguing over this many grains of powder or that many of projectile or this or that new firearm or "tactical accessory." I guess with ammo costs these days talk is actually cheaper so.... ;)
For a non-pistol weapon in .45 that used that round with a suppressor, google "De Lisle Carbine."