Hypothetical: If privacy coins get banned

If privacy coins were to get banned by all CEX’s… assuming DEX’s pick up the slack, would this create a fungibility problem for Bitcoin? Would BTC exchanged for banned privacy coins become “blacklisted”?

Why should we care about BTC at all?

BTC’s poor fungibility is good for privacy coins. If BTC’s weakness is exploited in the scenario described above, that would undoubtedly be bullish for Zcash.

But I’m not quite sure how DEX’s work re: transaction records.