I don't know...can't the parser be like only use-able on a premade party like pf? And make it as an option in the duty finder like how you turn on lootmaster? So if someone joins a party that turns on the parser, everyone will get to see their parse/eachother's parses, otherwise the parser is off for everyone in the party. If you join a parse-enabled party, you are basically accepting that u may get criticized, if you don't want to be criticized, just join a parser-off party? I think something like that could work, while I do see most higher end content pf like ex trials and savage raids people will usually ask for parses. But then again, if you are doing ex trials/savage you likely want to see your own numbers and improve yourself anyway, so most party doing those would likely have parse on.

TL;DR
It will be just like you get to choose to join a lootmaster party or a non lootmaster party.