That is because most people only know the Phil Collins fronted era of Genesis, which was massively commercial.
Which is criminally unfortunate on two parts. Obviously the Gabriel era led genesis is most known to be the proggiest (I love made up words). But, A Trick of the Tail and Wind & Wuthering we’re far from commercial successes and fantastic in their own rights. I would also say up to We Can’t Dance, which is utter tripe, their recordings still had nods to their prog past.
As far as PF… labels are labels. Who cares. But, I still consider Animals to be a prog masterpiece- for whatever that’s worth.