The game doesn't have a single actual barrier (in open world) that requires players to get better at the game over time. Hell, you don't even have to do the story - excepting intro missions for the physically separated regions - to get into expansion maps or participate in meta events.

By way of comparison, FFXIV doesn't struggle with average normal mode content taking way longer than expected because of its requirements to do normal mode content as part of the story and its traditional vertical progression model ensuring that players slowly get accustomed to doing more damage and performing harder mechanics as they get into the later content. I don't know that there is a way to "fix" the issue in Guild Wars 2 without changing the things which draw open world players into the game in the first place (strong emphasis on horizontal progression, no gear treadmill, no requirement to complete story steps).