The problem is map control. If you can't hold a resonable proportion of the map safely you'll lose in the long run. As Bentguru says you don't have to charge insanely in to be effective. All you have to do is ensure that you end the initial part of the game with a significant proportion of the map compared to your opponent without having lost much more than them.
The thing is, there IS NO LONG RUN.
My average game clocks in at under 5 minutes running rush, in 20 games I've yet to see a single person beat it. I don't abuse the VTS1, but rather run infantry (about 60-70 APC's inside of 1500 points, plus certain supporting units). I don't doubt it's beatable, but besides throwing down the specific counter that would get thrashed by another army (most likely composed of hordes of equally cheap units), it's just not going to happen.
They shred cheap armor, they shred light vehicles, (expensive armor has absolutely no chance, it doesn't fire fast enough). I have AA to take out choppers, and best of all the APC's all move 90km/h or faster and require no fuel to get to an enemy base. Flamethrower tanks are effective at stunning APC's and routing troops, but usually the backup units knock them out, or there's just too many APC's with rocket firing troops for them to live long.
Maybe I just haven't played anyone good, but tbh I would have normally lost at least ONCE by now. It's just retarded how well the cheap units rush works.