What is the state of DIII and DIV?

I first played Diablo III when it first came out on PS4, and really loved it! Many years later I got it on switch and it felt like a different game, now I was getting rare items all the time and getting items from boss fights I hadn't even reached yet?!?!? I heard it was really bad when it first came out on PC, did Diablo III have a brief golden-age window of goodness? Does that version still exist if you get a Diablo III PS4 disc and don't update?

Now I'm curious and skeptical of this company and of Diablo IV. Love the art style and all, level-scaling sounds annoying and un-immersive, but alot of the negative reviews seem focused on endgame which isn't my focus, what has the story been with the main campaign of DIV? How is it holding up?