Another thing I noticed is getting more common among RPG Horror Stories. When once it was common to see entitled players complaining the GM is not running the game like Matt Mercer runs on Critical Role, I have lately seen quite few stories where problem GM tries to use that to deflect criticism. It's usually the type to be acting creepily towards women, both in and out of game, enjoying juvenile, overtly edgy humor and/or insisting of all kinds of bigotry for "historical accurracy". And when the players confront him (as it's almost always a guy) about it, he's going to say something like "Stop sucking Mercer off, this is real D&D!" or "Go play at Matt Mercer's table, if you don't like it!".
While, as usual, there is possibility these stories are fake, I can see these being true - the kind to engage in those specific behaviors is also the kind to grab on buzzwords or try to twist real problems to deflect criticism.
The edgelord DMs who say stuff like this tend to forget that D&D is in many ways meant to be a better world. Where slavery exists, for example, it exists as something that evil people do and heroes stop. If you're participating, you're not a hero; you're the asshole the heroes are there to stop.
Bigots exist in our campaign, but its because we utterly enjoy putting them in their place.
D&D has hell. It used to be that the fastest-reproducing races were also evil, sending more and more people to hell.
Looking it up, the creators were Christian, so maybe they thought real life was even worse, but D&D was always intended as a crapsack world. If you want to play one that isn't, great. Just be prepared to rewrite some major lore.
D&D generally is a game of heroism and hope. D&D's hells aren't the hell of out world, nor do devils serve the same role. Different settings have different themes (the style guides are useful for insight) but overall, heroism matters.
And if one likes and gets power enough, one can even descend into the hells to punch the devil himself in the face.
I've heard campaigns don't usually make it to a very high level. How often do you kill the evil gods and free the souls in the lower planes?
Depends! 5E is broken at higher levels so rarely there. I've had a few complete campaigns in older editions though; a group with insanely high levels completed the Throne of Bloodstone and another custom campaign closed out after saving reality itself. As for killing gods, once. One of our PCs ascended to godhood too. For the hells, that's never been an overall goal. Freeing good souls, yes.
So in short, it's a crapsack world, and campaigns rarely involve fixing it?
There was a campaign that Puffin Forest did where there was a treaty between celestials and fiends that was stolen reigniting the war with the intent that the upper planes would win. But the guy who did that was the antagonist. The players were trying to preserve the status quo.
Maybe in your campaigns, but that's absolutely not how the FR are designed. But, don't take my word for it. Per the official FR style sheet:
"The Forgotten Realms is a hopeful setting. The good guys will eventually win. ... While not every moment of a story or image in art should be hopeful (the villains need their time in the spotlight, and bad things do happen), keep this tone in mind."
They don't even have stats for the gods. The only way players could win in a way that fixes the cosmology involves heavy homebrew.
I think when they said "the good guys will eventually win" they meant like stopping this particular big bad from doing whatever they're trying to do. Not that they'll replace the gods, make sure every afterlife is paradise, and find a cruelty-free alternative to the Wall of the Faithless.
They only just recently made an adventure catering to high level characters. 2E, 3E offered stats, so clearly they intended there to be a path.
It's clearly not a priority if they're only just doing it in 5e. They expect most players to play in a crapsack world and leave it a crapsack world. After all, if it wasn't a crapsack world there'd be no need for heroes, and they want a persistent world instead of having it always end after the players finish their campaign and fix it.
Nah.
You're taking a design flaw as something intentional.