People will take the easiest path to achieve goals!
This is not an objective statement. The entire crux of ChiefCurahee's argument for level sync is based on giving those that don't want a PL a way to level from 1-50 in a party. That entire post did nothing to invalidate any of his arguments.

You still have not shown any downsides to level sync that aren't already present within XIV's current game mechanics. To the contrary, you suggest that the status quo should remain over the inclusion of a feature such as level sync.

You make the wrong assumption that every new player's goal is to get to 50 as fast as possible.

Regardless, you admit level sync has it's advantages and quite frankly that is all that's required.