lack of such user base, best way tho 

 a better way, but very little user base because a) Tor traffic been blocked b) Chinese not accustomed to non-kyc trades and fraud is too easy.

there's a dead loop here, lack of trust --> KYC --> centralization --> less trust between plebs --> more centralization.

I'd like to see a nostr based p2p exchange. 

 people most probably trade on KYC exchanges like binance and okx, (i know it's awful) there are only 3 options for the payment, bank transfer, WeChat Pay and Alipay, all with in fiat. 

 I think I missed your question. 
*they* monitor individual tractions in real time. once a whale selling Bitcoin get a big influx in their account, they simply suspend the flow for the "security" reasons.