Qb6 lines are very reasonable of course, a lot of strong players have played it.
If you've prepared the lines, then sure, I see how your white opponents would struggle vs your long term ideas and they're passive.
Sometimes in blitz I get tired of having a nice 0.50 edge I'd enjoy OTB, only for it to not amount to anything. I don't go as far as GYG with the aggression, but I do like something a little more unbalanced.
I wager when I hit ~2000 I’ll tire of playing the same thing against the London and learn the KID approach or an early d6 Nc6 Bg4 e5 approach as mentioned, but currently I’m content to take a shockingly large amount of easy victories and take the rest to positional middlegames and endgames, something I struggle and need the experience in.
Qb3 loses to c4, Qc2 loses to Bf5, b3 loses positionally,
1.d4 d5 2.Bf4 Nf6 3.c3 c5 4.Nf3 Nc6 5.e3 Qb6 6.Qb3 c4 7.Qc2 Bf5 is good for black, yes. (I don't know the move order, just getting to the position).
But 6.Qc2 (without 6.Qb3) 6...Bf5 7.dxc and white is fine.
I don't see how 6.Qc1 or 6.b3 are so bad either. Sure it's pleasant for black, but it's kinda boring.
Yeah, against 6. Qc2 I usually go with 6… Nh5 or 6… g6. 6. Qc1 is solid for White, but Black has a rather decent initiative and space advantage, while White is going to have a few issues fully developing. 6. b3 isn’t fully solid. I can’t remember off the top of my head the refutation, but even without knowing it, I know White is pushing A LOT of pawns in the very early game, and the whole queenside becomes a target if White isn’t very careful.