The issue with Twilight Clerics and other WOTC-published broken stuff (Silvery Barbs) is that they're all considered default in D&D Beyond. If it weren't for D&D Beyond, it wouldn't be a problem. But players expect that if its in D&D Beyond, they can use it, and that ends up a big mess.
DDB not having any sort of way for the GM to limit source material for a campaign so players can't select anything outside of the GM's selected source material is a problem (yes, I know it looks like it has a setting for this but that setting doesn't work – if a player owns a source, they can access that material in the character builder rergardless of what the DM sets for campaign sources).