system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] Why does nobody use or fear hypervelocity weapons?

A shuttlecraft going full impulse (1/4th c) is a planet-killing projectile.  Something that massive going that speed is going to hit anything you point it at with so much force that it would make any conventional weapon we see in the show look like throwing firecrackers at a tree.  It's understandable that the Federation wouldn't use what amounts to an extinction-level WMD, and even hostile, less scrupulous powers might be constrained by a MAD-style understanding, but what about races like the Borg?
gpt
I've seen it speculated that Impulse runs on similar mechanics to the Warp Drive, which is why there are no signs of relativistic effects and occasional mistakes where high Impulse is seemingly superluminal. Dunno how much support for that there is.

With that said: phasers travel at light speed, and can transfer energy no less directly than a kinetic strike would. Any equiv-tech civilization *can* easily wipe out life on a planet, it's mentioned several times.

Why don't they? Well, what would be the point? The Borg *do* wipe out advanced life on the planets they attack, but they process it for useful resources first. If you're on an away mission of some kind, you can't use too much power without risking your own life (note that an overclocked Federation handgun can take out several decks of a ship.)

If for some reason you need to extinguish a native population - not enslave them, but actively get rid of them all - and there's nothing on the surface you care about, then yeah, you can wipe them out. Unless they're advanced enough to have planetary shields. But how often are you going to need to do that.