P2P is better suited for everything. Every peer in a P2P platform can be a relay. When you relay a message your IP is not directly associated. Even then things like onion routing in a P2P platform are totally possible with the added benefit of more nodes. Infact the lack of fixed static nodes makes network attacks ie logging ips at the routers or servers much harder

No offense but have you considered the viability of keychat? Playforms like signal, matrix and more hit scaling and funding issues, even telegram would have this problem. What technology stack can scale to whatsapps 3billion users tomorrow with no costs or service interruptions? What tech stack is unaffected if AWS or any data center goes down?

You should know the answer P2P