Are we playing the same game? MSQ is ~95% "watch this cutscene by yourself" and ~5% "oh look here is a 15 Minute Dungeon/Bossfight you can play with someone else". This starts off as not so bad as there are quite a few normal over world quests in the beginning that you can share, but that becomes less and less as the game goes on. (if I remember right, it has been a hot minute since I last experienced ARR)
With how much the amount of overworld gameplay quests having been minimized over the years, there is no real "playing together", doing the story with someone else means waiting for them to finish their cutscene so you can mount up and walk to the next cutscene dispensing NPC together, until a dungeon comes in sight.
When a group of my friends last brought someone into the game (during early EW), that person was desperately hoping for more content like PotD to play together for extended periods of time, despite having a small group of people to run content with. We lost that person because they felt too isolated when playing the MSQ, even with people around.