These comments make me think that the OotA campaign isn't really an incredible outlier in terms of this group's style. It seems to me that the power level probably creeps up a little more with each campaign in an effort to maintain player interest and engagement. Celtavian had to give away so much in the OotA campaign that any hope of game balance has just been totally destroyed. He said himself that he wants it to be epic and memorable. For a group just starting out, the stock version of Out of the Abyss will be more than epic and memorable enough. Players doing this for 20+ years now have already slain demon lords. Multiple times, probably.
That's also why I think the game math is far down the list of the problems Celtavian is having with his group. It starts with the increased character building power, the character-buffing houserules, and the incredible magic items that have to be incredible in order for them to be even remotely memorable. When you've been playing for 20 years, your fifth Holy Avenger doesn't seem very special.
I don't think Celtavian needs Mike Mearls and Jeremy Crawford to think harder about the game math so much as his group needs a break from the D&D paradigm. If they can't think about how they play the game differently (no small task, to be sure), then it does seem that a different game might be most appropriate.
Here is my problem with the game math. Or why it frustrates me. It does have to do with my players as well as the rules. So it's a bit of both.
Here's the usual interaction:
1. New game comes out.
2. We buy books.
3. We play campaign out of the box to learn game.
4. We usually play with feats and multiclassing, so we allow it.
5. Players start reading forums and testing combinations.
Here is where the problem starts
6. They start using any game exploit/combination they can find to give them a huge advantage. They always exist in nearly every game system including 5E.
7. I note the problems with the game math. Sharpshooter plus
bless plus magic item plus Bounded Accuracy equals recipe for easy killing of everything with limited DM ability to counter.
8.I want to tone it down.
9. Argument ensues.
10. I get pissed off at the game designers for allowing such a ridiculous combination to make it past them. It is so easy to see that -5/+10 damage, no penalty for range, and no penalty for cover all for one feat is way too powerful a combination. It's as obvious as the Great Wall of China if you were standing in front of it. Why make nearly every other feat reasonably balanced for game play, then insert a feat that causes such a ridiculous game issue? I never understand it.
11. Rinse and repeat for
wall of force or
bless or Aura of Protection.
Then I end up in all these arguments over game rules that should have been vetted beforehand. Aura of Protection should have scaled with level maxing out at about +4 or 5 at the very highest levels.
Bless should have been a flat +1 with perhaps a boost for using a higher level slot.
Wall of Force should have some kind of Dex save to evade getting encased. But nooooo. Game designers don't think so, so my players don't want to change it.
I could avoid a whole lot of this if the game designers would just pay more attention to problems and vet them prior to release. My players are generally "by the book" players. They let me put in some house rules to take care of problems, but we prefer not to have too many. I'm forced for the sake of continuity to follow the rules as written and interpreted by official sources. When those rules cause problems, I have to live with it or quit gaming. I don't like either option. The best option would be the game designers cleaning up the problem rules, so they don't cause a break down in the game math. I can't expect that either because they don't bother to test the game past level 7 or so the vast majority of the time.
So I end up in these debates over game rules I know cause problems, but only a handful of people that play the game the way my players do understand. It seems like a lot of DMs have players that don't mind them altering things if they are causing problems or don't bother to find every mathematical advantage possible instead focusing on story, role-play, and general fun. But I have power gamers that love to exploit the math. They always find the exploits, every game. Since I DM the most, I always get to deal with them. Boy, I wish there was a game that had vetted every exploit.
At least I told them next campaign I'm toning down Sharpshooter and they agreed to it. I think my fix should bring that feat in line with other similar feats.