I do agree with one of your points: What counts as development is not only whether the piece has moved away from its home square. I remember learning a lesson from Yusupov where he claimed in a certain position that White's knight on e2 was not really developed, since it was badly placed there. Therefore, White should play Ne2-g3, which he called a development move. However, that does not mean that Ng1-e2-g3 would count as two development moves, but rather that Ng1-e2 was not a development move, while Ne2-g3 was. Putting your point to the extreme, one could claim that White could follow up with Ng3-h1, and that the manoeuvre Ng1-e2-g3-h1 would count as three development moves! I hope you wouldn't agree about that...

Furthermore, even if you use a classic, generalized way of counting developed pieces, I wonder how you can claim that Black does not have a lead in development after 9.Bxb5+ Bd7 10.Bxd7+ Qxd7. Using the generalized way of counting which I learned as a child, White has two development points (one developed piece, and he has the move), while Black has four (three developed pieces, and the bishop is free to move). More sophistically, you could say that Qd7 does not count as a fully developed piece (it might prefer to be on c6, for example), but it is still better than having it on d8, since Black is now free to put a rook there, which he almost certainly wants to do. Also, Black's knights may be better placed than White's, since Black can easily chase White's knight away by f5, while White can hardly play c4 to chase Black's away.

Finally, Black's compensation for the pawn is not only based on a lead in development, but also on the pressure against White's d-pawn. White will probably have to play d4 soon, after which that pawn will be very hard to defend.

If we can  define the move sequence Nf3/Ne1/Nd3 as  developing moves then the understanding of  development must  change.

Change it if you wish, and if your theory is correct your results will improve against non-believers. Personally I'm more inclined to prefer to have pieces on their best or least worst squares and if that's the starting square, it's a saved tempo. I'd see development rather more as a question of getting pieces to their best squares and generating threats as quickly as possible.

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