The Leveling Problem explained.

[Jojoya]

Because the game never once through the entire playthrough of the MSQ requires you to properly play your job, There never is a dps check or anything where you actually need to think for a bit or practice(excluding certain sequences where you are forced to play different character, so you don't really know what you are doing, and even then you can lower the difficulty in case you fail.)
You can beat all teh trials even if you instantly die because the other teammates just kill it for you.

What MMORPGs do in leveling content? Challenge requiring knowledge of how to play a job tends to only exist in the end game side content.

There's the other issue of "you can lead a horse to water but you can't make it drink". It doesn't matter what tutorials a game has. If someone doesn't want to learn, they won't. Those interested in learning how to play better will. Some players might even learn and still play incorrectly just because they can.

It's an old argument that goes nowhere because it's useless in an online game. Don't like how well the random players you get matched with play the game? Create a circle of friends that you trust and play with them instead.

Having just gone through EW myself, I can attest, this isn't 100% true. With intention to only ever take MSQ (and MSQ duties) exp on my main job, there were a couple gaps that required a few FATEs be cleared to bridge the levels.

Part of it depends on how you play the game. If you're playing several hours a day each day, you're going to miss out on most of the rested XP bonus that bridges those gaps. If you're playing 6-8 hours total a week, it shouldn't be a problem.

If you don't own the next expansion and reach level cap for the expansion you do have, that's also going to contribute. Even if the amount of XP earned from patch content is small, it does add up and you lose it if you're doing the patch content while level capped.

I can guarantee that making such a tutorial mandatory for end-game gameplay after each expansion releases would tick off quite a number of high-end players. It would, however, remove the need for the so-called Mentoring System, so that might be a plus.

The Mentor system isn't about teaching others how to play their jobs (though that can be part of it if a Mentor wants to share what they know). The Mentor system is to help new players with general game basics. Where is such and such located, how do I unlock this content, what do I do to get this item, this queue is too long can someone help me get this done for MSQ, etc.

What SE needs to do to fix the Mentor system is remove the rewards.