If you play a Sabbat chronicle set in 2017, you can't play Tremere antitribu, because they don't exist anymore: "can't play" means "all Storytellers I asked would disallow such a thing due to Metaplot". You can't either play Salubri, except probably for Salubri antitribu if you are Sabbat-aligned. A Camarilla chronicle, even if you play Gangrel, would leave you with various social disadvantages, e.g. you don't have a Primogen. Ravnos were almost annihilated, some still exist, but no more than 2 can be in one coterie/pack, as they frenzy when they see each other.
Not even mentioning countless bloodlines, most of them not available for standard PCs for some reason.
However, I don't see any real benefit in that. What problems do Tremere in Sabbat and Gangrel in Camarilla cause? Why does the Metaplot render many options banned?