Insecure (you get everyone’s IP addresses, if you find a vulnerability you may be able to execute code on user’s computers instead of just a server)
Prone to significant lag (one person’s bad internet can affect everyone).
I’m sure there’s quite a bit more reasons that I can’t think of now though
While this is true, the chances of it happening is pretty rare. Just because you have my IP doesn’t mean much. Sure you can scan for stuff like open ports and you can easily ddos in a lot of cases, but running a program on another players computer takes a lot more work.
I believe most of the games in the early days of Online, for consoles, were P2P (flashbacks of people shouting “host advantage!”)