This isn't even the real middlemen we should be worried about. As for what happens in the general exchange of cryptos for cryptos, we can see that as buying from the house. The exchange charges commission to give us that service. The real issue is the exchange of cryptos for fiat using the P2P feature, even on Binance. Despite the fact that merchants are verified and their details held by exchanges, you still get the greedy ones among them trying to scam those they're transacting with. A few days ago, while transacting with one on a reputable exchange who claimed he had sent payment and that I should release coin. But that was a lie. He didn't send any cash. I confronted the thief and he immediately cancelled the trade. Without middlemen in P2P, scam will kill the industry. I could've been scammed by that buyer if there weren't any middlemen (who held my coin) and I wasn't extremely careful too.

I understand the scenario you painted there but that can be very risky too. To get to that point of trust, one must've done series of transaction with the other to enthrone such trust. Nobody should rush into trusting anyone by assurances of mouth. Let action prove its deeds.