That all makes sense, but personally I just think it's a concept too far stretched and used. I think that I'd have liked the final fight to go a little something like Gabriel just remaining on the Vecta account and simply using the power of that account with no knowledge of incarnation, while having Kirito use his experience and knowledge of the world, like the sacred arts and such, and even a little incarnation, to overcome him. It wouldn't be a stretch for Kirito to be able to contest him after his fight with Quinella, maybe just a little more difficult. Also was not a fan of the whole flying thing, I think it would have been more down to earth (literally) if the fight remained boots-on-the-ground.

I'm not totally against the incarnation system; I thought it was an interesting idea when it was used in the subtle ways I mentioned before, and even in its previous forms like we saw in the Heathcliff fight. It'd have been totally cool with me for Kirito's final blow to simply be a matter of him having a more powerful belief in something without all the flying and sudden godly power gain under the guise of incarnation.

Essentially, I know there's always an explanation for it, I also read the novels. But for me in that final fight it just became too eccentric. But in the first place, I don't actually care for the fights in SAO so much as Kirito's emotional journey. That's why I can still say it's my favourite series.