But why?

say what you like about antidisestablishmentarianism; at least it's an ethos

Somebody obviously coined the word as a self-referential joke. And somehow it stuck. That makes it memorable.

Speaking of things that stick... arachibutyrophobia is the feat of getting peanut putter stuck to the roof of your mouth. (I admit I had to look that one up, as it's not nearly as memorable, though I knew the word existed).

They are Welsh?

I too can say it and I'm very English...ish. LlanPG is a tourist attraction and a great example of an amateur advertising idea smashing it!