I think Nc3 is a bad idea, because what if black plays b4?
Um, we have a better chance of winning? That's what usually happens when the opponent plays bad moves!
We'd be stuck with 11. Nb1, which is a waste of time,
Boris Spassky would want a word with you.

After 12. Nbd2, Black's queenside is extremely weak.
Nd1, which is arguably counter-intuitive,
But allows the very strong 12. Ne3.
or Ne4, which is an instant trade-off, also putting two of our pawns on one file.
This is the best refutation. It's a decent trade for White; that Black knight is quite annoying. But more importantly,
it opens the d-file at a moment when White can immediately take full advantage of it with the rook and queen. This far outweighs the weakness of doubled pawns, which is generally overrated by novices. White is clearly better after 10. Nc3 b4? 11. Ne4 Nxe4 12. dxe4 ... 13. Rd1.