Your idea of "normal people flush with cash" is ... private equity lol. It's incredibly common for companies to spin off random LLCs to buy up whatever they want.
Putting a rental in an LLC is very standard advice for anyone buying one. You've clearly made your mind up about this and won't change it if you think PE is buying up all these homes when you linked an article saying 5 public companies with $110 billion in market cap with access to almost unlimited amounts of cash only managed to capture 1.3% of the market.