But original question does state that PF IS more popular.... what am i missing?
Pink Floyd is more popular. They sell more stuff and have more name recognition (globally, and overall). This is measurable.
Saying something is more popular isn't the same as saying something is better. McDonalds sells way more food and has way more name recognition than Chez Panisse* (fact!). By saying that, have I just said that food from McDonald's is
better than food from Chez Panisse? Of course not!
My favorite musical artists are considerably less popular than either Pink Floyd or Rush, which is really saying something as David Gilmour is my favorite lead guitarist of all time, and Geddy Lee is right up there among my favorite bassists. I choose to listen to High On Fire easily ten times more often than either Pink Floyd or Rush, though.
To me, High On Fire is "better" than either of them, at least when it comes to what I want to listen to; clearly that's just my personal taste, which no amount of facts will change.
The actual question here as I understand it could be rephrased as "why do more listeners personal tastes tend toward Pink Floyd rather than Rush?" 20-some pages into the thread, the answer seems to be something like "Pink Floyd's music has more in common with what most listeners want from their listening experience" or "Pink Floyd's music checks more boxes for more listeners." Someone mentioned Pink Floyd's head start, but no one has really addressed the business or marketing aspects, which I suspect also have much to do with this.
I'm surprised that this bothers Rush fans—ostensibly cerebral types—to such a degree. Isn't part of the fun of being a Rush fan feeling like part of an exclusive group that "gets it?" I know I derive some satisfaction from my taste for the relatively obscure.
*and I'm not saying Pink Floyd is McDonald's and Rush is Chez Panisse! I wouldn't eat at either restaurant, but I'll happily listen to either band.