But “okay boomer” has just become a bland, flavorless retort that gets said by anyone to anyone for any reason.

It isn’t an expression of frustration at an audience that rejects facts and reason, it is a pithy retort that gets thrown out to say “STFU” to someone in slightly more polite terms.

Like, the root of this isn’t unfair. But as with so much internet lingo, the initial intent has been polluted by online gooners who latch on to a phrase and use it as a barb rather than to convey any particular kind of coherent message.