Under original Dark Age rules (300 point games), if you took a big 'Mech, that's pretty much all you took.
'Mechless armies dominated. This point was driven home by the army compositions at the World Championships, where something like 5 of the top 8 players had 'Mechless builds, and the few that had 'Mechs only had one and it was basically a chargemonkey.
Even in a 300 point army there was plenty of leeway to keep the armies balanced. In theory, a big 300 point mech was supposed to be equal in combat value to a swarm of infantry and a formation of tanks that cost as much as that mech. In reality, having the flexibility of using multiple orders on a variety of units every turn gave the "mechless" army a significant advantage over a single unit that can use only one order and must rest frequently.
That was the lesson of the metagame the top players were showing us. The winning armies chose units that could perform more than one type of action. To gain several extra orders by rolling dice every turn is not wasteful when they are used on two transports dropping a tank and three infantry in a range attack formation, and you still need to be able to push something in to base contact so the Target has difficulty shooting back at that formation. And there are always supporting units that need to be occupied with saving their own butts.
So, yes, a swarm of VTOLs and tank drops that can out run and out range the mechs and tanks they shoot at, does look pretty powerful as a mechless army. But, it still required good tactical play from those top players to make it work. I'm sure none of them had an easy time of it, after all, they were all that good.
That's one of the things that made the Game fun. Developing and discussing new skills and strategies that improve on or help to destroy what we all know as to be "Tried and True". Does the Pog Warrior always brag about winning every time? Only if he's never played against an army that can be in his deployment zone faster than he can shoot at it.
GC