"I do not understand why everyone thinks that a prime is the only way to go for portrait photography. This is a relatively recent development with the copycat trend of shallow DOF and out of focus facial features. "
So true. At least for me as it has been my preferred way of working ( using smaller lighter weight, larger maximum aperture to make focusing easier even if I shoot well stopped down, single focal length rather than bigger, bulkier and heavier, zoom lenses with smaller maximun aperture zooms) for only the past thirty years. I guess I'm the cat everyone has been copying.
"The 70-200mm f2.8 is more effective in more situations than a 85mm prime"z
I have both. Both have their place. With portraits I want to get the gear out of the clients face as much as possible and let's be honest: any 70-200mm f/2.8 lens is a big hunk of metal and glass to stick into someone's face from a short distance away and while backing off to shoot the same framing of the main subject at 200mm it has it's aesthetic advantages (compressing perspective, moderating the degree of background detail), the further away I am the less psychological contact I have with the sitter.
"With Canon another very nice lens is the 24-105mm f4 IS lens."
I've had three and rented two or three others. None met my criteria. Nice decent lens. nice range of focal lengths, but ultimately it's a lens that doesn't work for me.
"The more you can crop in camera the less post processing work will be needed and with wedding photography the time required is already way out of hand. In this regard digital has been more of a curse compared to the days shooting weddings with film."
On that I agree with you whole heartedly.