That is common knowledge. However, what the game says it's doing (in one, confined, narrow place) and what it's actually doing are not necessarily the same thing. Saying that D&D is S&S because look at Appendix N; it's full of S&S influences is, at best, a very circular argument, proving nothing.
At best. And for a "best" scenario, that's obviously not very good.
I did some analysis of the game itself on the OP. Ok, I'll expand.
In AD&D by EGG:
1) Being good or evil is just the same for survival, progression and success. Being good or even beign the protagonist, grants you no special consideration. You are all by yourself. The system or the DM does not help you out.
2) Power and luck is the only thing that will define a battle, not your higher or better morals. There is no cosmic justice in the D&D world. If you are stronger, more resourceful and lucky, you win and nothing will punish you for that aside from an revengeful enemy.
3) Advancement is by killing and looting (1 XP for 1 GP). Killing an evil or a good guy is just the same. Looting from an evil temple or from charity is just the same - no moral judgments on the source of XP and $$$.
4) No XP given for quests. So if you help the peaceful villagers, they is no XP from that aside from what they pay you. If you kill them and take their stuff, you'll win just the same XP and the extra XP for the villagers. Then you can go kill the evil monster and take his stuff as well. Nothing in the system punishes you for doing that.
"Quest" is a spell 5th level cleric spell that works like a curse, more than something noble and idealistic to do.
5) Gods have stats and can be killed. They are just super-powerful monsters.
6) Nowhere it says that being evil is against the premise of the game, as the 4E books say. You even have an evil-only class: the assassin.
7) Guidelines for demon summoning, totally available for the players.
8) More randomness, more unbalance, more weird unexpected stuff. No forced balanced encounters, no prescript treasure.
9) The only reason for being good, is to have access to the nifty paladin and ranger abilities, and too be able to use some magic items reserved for the good guys - so it's totally in self interest, no real altruism.
That makes the game strongly sword & sorcery in my eyes.