I don't regard myself as an expert on South Africa (I've been 3 times for a total of 4 months) but your generalisations do surprise me. Conrad is a 5 star hotel and attracts people who can afford it just like 5 star hotels around the world. As you say, YMMV.

Added: A note on the website says that access to their beach is temporarily suspended because of the devastating fires they had last year in the region. That might explain why they didn't mention it to you. Other beaches around Knysna are apparently open.