Originally Posted by
Koyote
No. You'll get tired of the sound of pebbles rattling under your fenders...and the worst-case scenario is a larger rock or twig or something getting jammed between tire and fender and causing a crash.
Also, depending on your frame's tire clearance, fenders might force you to use narrower tires; e.g., if 40mm is your frame's limit, fenders will likely force you to put on 35mm or even 32mm tires. (Wider is better for gravel.)
Just wash your bike if it gets dirty.
Fender farts, they're called. If the fenders are close, it's a zzzzzzzzzzzip sound. The alternative is, that pebble (and it's smaller cousin wet grime) is thrown against the frame or driveline or your feet.