Implicit in your statement is the claim that you cannot acknowledge the existence of a percentile without believing any given feature of your domain can easily

Implicit in your statement is the claim that you cannot acknowledge the existence of a percentile without believing any given feature of your domain can easily satisfy that percentile. That's a non sequitur. The conclusion that follows from that one is also very strange, because it would mean we shouldn't bother quantifying things (or having a name for them) if they can only be expected to happen extremely rarely.