Doesn't seem to be that long to me. The Immortal set, written by Frank Mentzer and released in 1986 was for characters who "had transcended levels" and had power points and ranks, along with the ability to "literally [able to] cast any magic spell in addition to new combat abilities." and well as "their ability to construct their own personal "home planes"."
Not sure how you want to redefine that as not becoming a god, especially since the set included lore that: "once there were only three Immortals, who discovered the
multiverse, and decided to give it order and purpose."
Yes, TSR famously printed a lot of books. "They printed a lot of splat books to expand options" is very different from "you have to buy a new game every year" If you take every major revision of DnD that you are trying to lay out, that is 11 major revisions over 50 years.
A game you have to buy year after year would have fifty versions in that time. So your statement is still a massive overselling of what actually happened.
Your first sentence is a run-on and doesn't even make sense, let alone not having any backing. But sure, 5e then Tasha's SIX YEARS later and now a revision four years after that. I mean, shock and horror that they update the rules every so often. Should be like 2e where they made Holmes Basic, B/X Basic, B/X Expert, BECMI Basic, BECMI Expert, BECMI Companion, BECMI Master, BECMI Immortal, and THEN the Rules Cyclopedia. You know, back when DnD was DnD and they didn't just change the game and make it nearly unrecognizable, like this quote: "Lawrence Schick,..., felt that "Play using the Immortals rules is so different from low-level D&D as to be almost another game entirely.""
Oh yeah, completely unlike the old version of the game where you could make your own plane of existence and cast every spell possible. I mean, Wizards got... um... something! They can't do any of that and way less powerful, but they are just like superheroes! Unlike those 3rd edition characters who were so grounded they could run on clouds and fling mountains at each other. No barbarians get to rolls slightly higher skill checks! They can even read and negotiate with nobles!
Again, kind of weird that for all people's declarations that 5e is the most over-the-top version of the game... it may be one of the WEAKEST peaks in DnD.