HN is full of self-professed master negotiators. Just look at any salary thread. I am absolutely willing to pay a realtor to negotiate for me (and in general to have knowledge of the market and know how to find the real market price) because I suck at negotiating and have no idea how to do it.

Well, the average real estate agent is also a shit negotiator on your behalf. The incentive structure makes it so irrespective of the skill set. The agent’s primary job is to sell themselves to you when they get the listing not to sell your house at max price. On the buy side they are also incentivized to close the deal rather than make you do a wise bid. That said during a bidding war, if you are a buyer and your agent is a rando or you don’t have one, the seller agent almost certainly will give the last word to their buddies in the industry so you’ll lose the bidding war. That’s about the only value I’ve seen an agent provide.

I don't consider myself to be a master negotiator at all, but I can look at Zillow and know how much I want to spend or how much I want to sell for. The internet has removed a vast majority of the information asymmetry involved in house transactions.