Bigger proved in fact to be better.
The people who ordered these tanks to be designed were pencil pushers.
First they called for tender a vehicle of 1 ton and industry build it.
And then it goes on: 3 tons, 6 tons, 12 tons, 24 tons, each with a huge list of specifications like armament and armour. For the pencil pushers this is easy, they ask to get what war prooved to be needed. Bigger guns and better armour. So, the request is first, the realization comes later. The problems of a big tank, like suspension, sinking depth or the engine are not that obvious on the first glimpse. Nobody had tried that before. It all appeared to be a question of engineering.