Through P2P, you can get your coin/token without any charges, and if you cannot get it directly through P2P due to the lack of popularity of the coin, you can easily exchange the popular ones you can buy through P2P for the coin/token of choice with a reduced rate. This is what I do though, and it is cool unless you have another reason for doing what you explained other than for the charges considerations.
I used to think that the primary use of P2P is to exchange to cash, as there are auto DEXs that make waiting for the transaction to be completed in cryptocurrencies slow. Also, we are talking about trading, where the trader buys and sells cryptocurrencies for profit, and some types of trading require speed in executing orders and low fees in order to trade. It is profitable, so it is natural that most of the trading is in CEXs.