Can someone explain to me the main purpose of platforms like Localbitcoins, Bisq, Paxful, HodlHodl, Localethereum, Altcoin, Vicex? I try to look into Localbitcoins and see that people set demanding rules just to buy their bitcoin. Also, the price is usually more than what the current rate of bitcoin is. I'm really clueless about why anyone would use such platforms. What's the benefit?