I don't get the argument here. What's to stop a party from running some leves for an hour?

To me, parties have the edge still. Do eight leves for an hour, then go grind for an hour.

So what if a solo player can match the SP of a party for an hour once every 36 hours? There's still about 160-some hours in a given week for parties to out-shine a solo player.

If it's a matter of not wanting to spend too much time in the game, well, parties are for an extended duration, solo is for a quick in and out. There's has to be some lines drawn for a developer to create content with purpose.