Personally, I don't recommend it. Vinyl is a product that expands and contracts. If your're siding is dark, it's gonna move more than siding that's light.
By screwing 'things' to the siding that prevent it from moving, you MAY see kinks/waves in the siding over time. And depending on the style of your siding, think of what the area underneath the brace will look like once you screw 'whatever' down tight to the wall. It's gonna compress the lap (if you have lap siding) and it won't look too nice. I have a garden hose rack mounted to my vinyl. Underneath, I put up a 2' x 2' insert of plywood to screw the 4 corners into. Then, I drilled 4 holes 1/8" to 3/16" larger than my 3" screws. The screws sort of 'protrude' out from the siding so my hose rack kind 'hangs' away from the siding. I silicone-caulked the holes so the siding can move if it needs to. So, in doing it this way, nothing is preventing the siding from moving.
I would suspect that you could make almost anything work but usually vinyl siding has 'decorations' and such J-channeled around vinyl wall-mounts. For example, there are vinyl wall-mounts for spot lights and the siding is J-channeled around it. Otherwise, you'd have to screw the light mounts right to the siding! The same goes for wall-mounted, outdoor electrical 'boxes' and garden faucet hose 'bibs'. In short, the way I see it, unless you are able to safely mount whatever it is you're mounting by cutting out the vinly so it can 'move' (and then caulking), I wouldn't do it. Just my $.02. (I do see the rules being broken from time to time ...)