OK, I am break this down a little
I haven't played 3rd, so I won't speak on it, but 1st edition's stats for gods were weak.
It doesn't matter if you think they were weak or not, they had stats for gods, including greater gods. The heads of pantheons had 400 hp (2x as much as demogorgon) and a host of class levels and other abilites. Heck, Thor's hammmer did 100 damage on a hit (+ strength bonus).
2nd edition had stats for avatars only, and same with 5th right now. No stats are for the gods themselves, only their avatars.
This is incorrect (for 5e). Lesser gods can specifically be stated in 5e and we already have stats for Tiamat. Now, personally, i treat those stats as an avatar, but by RAW they are her full stats, not an avatar.
D&D does not give Gods stats for the simple fact that according to their rules, a God can only be killed by a God of equal or greater power in his domain where he is all powerful. They are all pretty much immune to mortal magic, and all but the most powerful artifacts, can create any spell at will, and literally warps reality around them.
This is not true either. There is no rule in D&D that a god can only be killed by a god of equal or greater power in its domain. That doesn't fit with the rules by RAW or the lore (if your not familiar, several gods have been killed in D&D lore, and not be other gods). I god would, in theory, need to be killed in its domain, but the rest is just not true.
3rd and 4th edition may have had stats for gods, but they had all of the 20+ shenanigans with the prestige classes and epic destiny nonsense.n 5th edition doesn't. At least not yet, and as far as I know, don't plan on making anything past 20 anytime soon.
I'm not sure what your point is with this statement. I also don't know why you continue to ignore 1e.
If you hadn't noticed, all of their campaigns they've been putting out only goes to 10. They are purposely keeping the game geared towards lower levels.
I agree with the general thought, but you got the details wrong, several AP got to level 15: HotDQ + RoT = lvl 1-15, PoA = lvl 1-15, & OotA = lvl 1-15
So, though you may not like it, D&D has almost always provided stats for gods, the only exception being 2e. 1e, 3e, 4e, and 5e have had stats for gods. It is just part of D&D. You can argue that sometimes the "official" stats are not as powerful as
you would want for a god (and I would agree), but claiming D&D doesn't provide stats for gods is just false.