DPS frustration

[Cold_Raven]

"No job is easier than another" is innacurate, or at the very least unproveable. my own experience shows I can tank and do decent dps (for a tank) far more easily while holding aggro and not dying. This would indicate tanking is easier. It might not explain the large number of awful tanks however.

This doesn't mean tanking is easier.
This means tanking is easier for you.

In order to show that tanking (or, anything) is specifically easier... you would have to show that significantly more people can reach an "elite level" with tanking than they are able to reach an "elite level" with the other classes. (If more people can do it on average... then it would be "easier.")

Is this information available?

I think FFLogs pretty much shows that all jobs can perform at an elite level about as good as any other.
I think they also show a fairly even distribution between the different classes and between "average" and "elite" status in each? But I'm not sure.

Historically, this game has had an incredible level of balance across all jobs.
There's always been a job or two that can be min/maxed to show an increase in value... but that increase is not very significant. It's generally the same kind of "increase" that can be gained by getting lucky with Crits or other random mechanics.

[Zojha]

In order to show that tanking (or, anything) is specifically easier... you would have to show that significantly more people can reach an "elite level" with tanking than they are able to reach an "elite level" with the other classes.

There's several issues with that assumption.
You focus entirely on the skill ceiling and ignore the skill floor and everything in between.
This leads to two big issues.
First, "elite level" is relative. If everyone could perform at an elite level, that level would no longer be elite, but the average. Average is average for a reason. The average performance would simply shift upwards.

Second, it means that even if you could be a functional (i.e. able to clear the content) tank/healer with very little skill and would require tons of skill to be a functional DPS in the same content, you'd still proclaim them equally difficult by your criterion because there's still room to go above and beyond towards the "elite" level.

And then there's a third issue that comes with using FFlogs as reference: By comparing DPS numbers for tanks/healers and DPS, you are technically not looking at the performance of the role for the first two anymore. You already take that for granted and only look at how much you can excel beyond that. That already implicitly assumes that tanking and healing is trivial on its own, whereas DPSing is not. As a matter of fact, if you use DPS as criterion for tank/healer mastery, the difficulty of those roles lies in not overdoing the tanking/healing, which again implies a lack of difficulty in tanking/healing as such. And if that's not the criterion you use, well... I'm not sure how helpful FFlogs is.

By using FFlogs, you are also muddling class mastery with encounter mastery, gear and teamcomp. Believe it or not, people who don't die do more DPS and not dying isn't a matter of whether you can play your job, it's a matter of whether you learned the encounter. The parse of the healer that doesn't need to raise the DPS is going to look a lot more impressive as well.

There's too many issues with that criterion.