So there's been some talk about the new 5E supplement having a laugh at grognards with a character called THAC0 the clown. I don't really care but as king I have to chime in on this.
It is unprecedented that there is something published in a D&D product (as non-canon as it may be) that takes the piss out of fans of that game, whether new or old. I'm not offended by it in the least, I wasn't going to buy the book in either case so they didn't lose a sale and if I was going to buy it I'd probably still buy it so they wouldn't have lost a sale. Collectivism/Completism runs deep in the hobby. I myself followed this for a time when I thought 5E proved the OSR won the edition wars. I own well over a thousand dollars of 5E stuff. Stuff I admittedly have been too lazy to sell.
I'm going to explain every single 5E book worth owning:
The core three
The original Starter Set
The Essentials Kit
Sword Coast Adventurer's Guide
The original Curse of Strahd
Tales of the Yawning Portal
Ghosts of Saltmarsh
Rime of the Frostmaiden
Tomb of Annihilation
Yep, that's it. And I put a gap because the first 4 things are actually great, the rest are merely decent. Why is SCAG great? Everyone hates it. That's why. None of the options are overpowered trash because for a tiny tiny window 5E wasn't going to be like 3E and 4E. Options were meant to make you different, not better.
As you can see, these books are mostly early 5E, and most are retools of 20+ year old modules. This is why The Mild Beyond the Bitchlight has to try to drum up sales with something to attempt to cause a public outcry. Basically the mediocre book needs sales because the last several books have definitely been seeing less and less sales.
So my response is: who cares? Let them keep circling the drain.