Of course you can make a complete, polished, high-quality game using 3DGS. If few poeple have really done so it's because it takes a huge amount of effort and planning to make anything more complicated than 3d pong, talent, and generally requires money. What you get are a lot of unfinished projects, and a few valueware-quality titles that arent particularly interesting. This is the cold, hard truth of indy game devlopment: most projects will fail.

But in reality, there arent many good, finished games using most of these other indy engines either. Name a good Torque game, Dark basic, BlitzBasic , Ogre, Jamagic, or Irlicht. I can think of maybe 1 or 2.