Tbf Spiffing Brit would find the needle in the haystack.
I understand your worries, yet there's a different balancing act that comes of it, which you can see, for instance, in Magic the Gathering Modern. If the paths towards OPness are many, the balancing occurs on those grounds alone. It is wild and out of control, even with banned cards, and I think that's what draw many players to it, while others avoid it.
In Civ 6 OP civs and leaders would be locked to the player picking them (unless duplicates were allowed? But duplicates are lame).
In Civ 7, even with theoretical OP combinations, factors specific to the game you're currently playing may still make some paths better than others. So not only are there more paths available by default, developments through out the game might make selection of one Civ over another the better choice, and this may be difficult to predict and plan in advance.