There's nothing wrong with limiting the available books used for a campaign. When I was recruiting players for a 5e 2014 game a few years back, I said PHB and XGTE were available for character creation, because a) it was a tabletop game and I only have a digital copy of Tasha's Guide, and b) I think some of the Tasha subclasses unbalance the game and I didn't want to go through the effort of rebalancing all of the encounters I had already created for the campaign. I posted the character creation rules as part of the recruitment notice, so if someone had a strong preference for a Tasha's subclass or species or content from third party publishers, they could seek another game that better suits their interests.
I'll withhold comment on the issue of more specific curation, since so many of the arguments being presented here (as in the other thread) assume bad faith on the part of either the players or DM. I do tend to use a homebrew world with established cultures when I run games, but most problems can be solved with open discussion and compromise. If one of my long-term players wants to run something that's not common in my world (e.g, aasimar or goliaths, which are new to the world as of the 2024 ruleset), we can discuss how they would fit into the setting. But to be honest, if a random player came to me in response to the notice above and said they wanted to play a genasi artificer, I'd probably pick one of the players who'd bothered to read the game announcement.
