I think Roger Waters is great, but Pink Floyd was an okay experimental band that became a great band a year or two after one guy lost his mind and another one was hired.Waters, the guy that wrote basically all of the lyrics after Barrett went crazy, and held the band together despite that tragedy said "this is over, I'm done."
Gilmour, who was added as a hired gun after their initial success then was given full member status due to his contributions, said "nah. It's my band now dude."
I don't see how your argument justifies that behavior. Waters didn't either and I'm of the mind to side with him.
Their initial success before Gilmour was certainly not going to carry into the 70's without some real substantial musical growth and refinement.
The partnership that Waters and Gilmour had was crucial to their best records no matter who was being difficult, they learned how to polish their material to a Gold and Platinum selling level together, with significant input by Rick Wright also.
David Gilmour was way past a hired guitar player by the time Dark Side of the Moon was released.
His presence and influence in the band seemed evident enough on Atom Heart Mother, Meddle and Obscured By Clouds.
By the end, it was as much Dave's band as it was Roger's.....if Roger chose to bail.
....In My Opinion.