I think a lot depends on how precise the track surface is. On an older bumpy track, front wheels touching can be the kiss of death. If you race on a smooth track and have precise front wheels, it can be OK. Just like GT40 says.
Cheater's old TFlex tome shows him using O-ring fronts on a solid axle that worked for him well, but that was then, this is now. Some of these new chassis aren't designed to use fronts, for a good reason. If there is a flaw in the track surface that catches a front wheel and upsets the car, you launch, hit the wall, the tongue is now bent, and your handling goes away. You launch again because your chassis is bent, and it just gets worse from there ……… until, eventually, you pull off and DNF. I'm saying this from a newbie's perspective. If his car launches every race, he will probably change hobbies to knitting sweaters or golf.
I've personally witnessed a scale fanatic who always preaches slot cars must have front wheels, during a race, tweak his front axle up on both sides to keep the front wheels from causing his car to de-slot. He didn't know I was watching him, but I'll never forget it.
There are so many ways to prevent front wheels to keep from de-slotting your car I cannot list. My local track has some classes where the rules say "fronts must touch and roll on the tech block"
. I pass tech every time. And my cars never launch. You figure it out
