My experience parallels yours after eating at a couple of his Padstow places. I did enjoy his earlier TV programs but feel he has gone off the boil and IMO he shows little insight into the food of the countries he visits.
But given the number of restaurants he now has in Cornwall it makes sense to use a wholesaler. Day boats from single ports just won’t deliver a consistent volume and range of fish. And the wholesaler is still in Cornwall and buys from local fishermen so its not as though he is shipping in fish from Nine Elms (London).
I suspect the criticism is really a disguised criticism of “the Stein effect” - the gentrification of little Cornish villages. I found Padstow to be interesting, certainly their are a lot of Stein businesses (Restaurant, Bistro, F&C, Cafe, Hotel, Gallery etc etc) owned by Rick and his family (including ex wife Jill).
But it also had great, if not better, places run by other chefs like Paul Ainsworth and Nathan Outlaw (in Rock). I suspect without the Stein effect these other chefs would struggle…and aren’t they all Stein alumni?