It's all they have left. It gave away the game for free. Everyone and their uncle can make their own D&D using the SRD (the Real Toolbox). So what does WotC have left to sell if not it's IP? The shared world(s) and branding? Why even bother with the PHB if you're not interested in the D&D...
Sigh. Alright. Here is the Quotes:
1. If it exists in D&D, then it has a place in Eberron. A monster or spell or magic item from the core rulebooks might feature a twist or two to account for Eberron’s tone and attitude, but otherwise everything in the Player’s Handbook, Dungeon Master’s...
3e? The edition of feat chains and prestige classes? The one where you could build an utterly ineffective character if you didn't plan your build down to the last skill point and constantly buy new +X gear 3e? I might give you AD&D (90% of your character design was done at level 1, unless you...
I don't want to find the paragraph again in the 3e, 4e, and 5e version of the Eberron setting, but the statement is based on a simple premise: there is no lore reason why something can't exist in Eberron. There is a reason in lore why I can't play an orc in Dragonlance or a dwarf in Theros, but...
"If it exists in D&D, it exists in Eberron."
Seriously, Eberron is probably one of the worst examples of limitations in D&D and that's intended. There are things unique to Eberron (warforged, Dragonmarks) and things that are altered (cultures of elves and halflings) but nothing (and I mean...
I don't find that true anymore. Maybe back in the old Red Box when you had to earn thousands of xp to make 2nd level that was true, but 5e is structured that levels 1 and 2 take one session each to achieve and are basically tutorials. It's more like skipping Weathertop to get to Rivendell.
As of your four examples (plus the original one).
1. I would probably walk from an all human D&D game, but of a game was not billed as D&D (aka a dedicated Conan RPG) I am less inclined. Put another way: I'm not going to bounce from Cyberpunk Red game due to the lack of aliens and fantasy...
That depends. Did you tell me that when you invited me or when I showed up at your game to play? If you told me "Remathilis, I am starting this new game that is going to be all humans and very GoT )or Conan)." I can say "yeah, that's not what I'm looking for" and no harm no foul. If you say "Hey...
Clever bait and switch. So first off, if you invited me to play D&D 5e and then pulled out the Shadowdark book, I'd probably leave for no other reason than that you lied to me, didn't feel I would play if you told me that was what we were actually playing and I couldn't trust what other ruses...
Yes. That is my standard.
Ten is what is in the current PHB, but that number would really be whatever is in the PHB you are using. But I'll be frank; it's NEVER just one. It's (warning: hypothetical example) "no Dragonborn, Goliaths, Orcs or Planetouched, no world tree barbarians, warlocks or...
I consider setting expansions books fair game for banning. I don't use Dark Gifts outside of Ravenloft, Dragonmarks outside of Eberron, and kender outside of Dragonlance. My walk proviso is for banning stuff in the PHB without a replacement for it.
No. I cited one example. Did you really need me to list every species?
My point was 1.) it's never just one species (or class or subclass or whatever); typical it's rather large list of bans and 2.) there are hundreds of optional species in 5e alone. If you cannot find 10 options out of the 40+...
Poe-Tay-toe, Poe-Tah-toe. You can have a focused, fully considered and intentional rational for why every PC must be a Lawful Good Human Male Fighter with Blown Eyes, I still won't enjoy playing in it.