balas on Nostr: seeing a lot of `p` tags with the third value marked 'root' or 'mention'. aren't ...

seeing a lot of `p` tags with the third value marked 'root' or 'mention'. aren't marked stuff exclusive to `e` tags per nip10?
shouldn't `p` tags have a petname at that index instead? nip1 does not say what goes on the third value but nip2 defines it as petname, at least in the context of kind:3, but I think it should be extended to all p tags for consistency.