Yeah, I had to roll my eyes on this one. I guess I can't imagine someone saying Halo 3 aged badly or what not when it was being played for years with an active userbase including myself and who competed compared to the quick flounder of Halo Reach and Halo 4. I feel you can still play Halo 3 now on guardian oddball, team slayer narrows, koth construct, ctf pit, and feel it is better than most shooters out today. I also felt a lot of your arguments are just to justify Halo 5, which was a very bad beta, where a lot of pros are unhappy about (go watch Twitch) like the movement feeling so slow and sluggish and so forth in Halo 3, which does not feel like that at all. It is still very mobile. The AR was fine in Halo 3. You can still kill a BR opponent if he is not good and as it should be, a BR opponent should beat an AR. I don't care if the AR is close range or not, a BR is a skill weapon and should be able to defeat an AR or a SMG in any circumstance. In Halo 5, this was severely compromised. The AR in Halo 5 is way too powerful with a battle against a skilled BR opponent being far too close with the former winning a lot. I know a 343 tweet has said otherwise but after playing, I don't agree at all. Halo 3 offered tight teamwork oriented play where the following Halo's did less of.
But yeah, on a proper netcode and registration, I think the Halo 3 BR is the best BR in the series and a lot better than 5. You hit it when you said in Halo 5 your shots actually counted and I agree here. The BR in Halo 3 was random only because of the poor netcode, but if they fixed that, it would be awesome with personality especially in a redesign with the pop.