Replies in no particular order to post or person who posted lol...

I must have missed the part where other hate tools were remotely relevant in situations where you can achieve decent damage output.
Warcry, Berserk, Defender, Yonin all give you more hate. Yonin on a more useful basis, but the other ones are good spike hate tools. On high defense mobs ninja has no real chance cause we will never be able to keep up with the DD in terms of hate giving abilities or just flat out damage. If your fighting a super high defense mob and doing very little damage you have to rely on gear and abilities to keep hate, where with lower defense mobs you can use those things as backup in case some idiot DD doesn't understand the concept of hate control keeps just spamming WS and eating the mages MP

Because most people look at the roles of jobs in one dimensional view almost everything. If one job does it better then to the community, it's assumed that that job is the only one suited. Anything less is undesirable or "gimp", doesn't matter if they're capable or not.
People have tried tanking with other jobs and also have tried using jobs like nin as a main DD. In the long run it just doesnt work cause there are jobs that can do those tasks more efficiently. Certain jobs have certain roles to maximize the groups potential instead of holding them back because someone wants to experiment. People experimented over 8 years ago to see what jobs do what best and that why we use certain jobs for certain things today. I want you to remember that WAR/MNKs used to tank everything till Zilart was released soooooooo ya, we have evolved from that point.

Firstly while I agree that certain jobs have the POTENTIAL to be better tanking certain mobs than other jobs, that does not mean that everyone of that job beats anyone else playing another job, simply due to the fact that people's gear will always differ from person to person (and you can't just assume that EVERY paladin out there has phys- MDT- MDB- and other such things capped, because as sad as it is the majority of players in this game have fairly lackluster gear, and also lack the skill to be able to use the right gear properly.). Hence the point of my post is to talk about general tanking gear, strategies, and providing insightful knowledge on how to properly tank, and use said gear, rather then saying "Oh well for this fight PLD is better so if you have PLD then you can win." because frankly that just brings about the notion that an AF geared PLD can beat out a perfectly good NIN on a certain fight simply because he's a PLD.
I agree with a lot of what you said and i never said job was the only factor in who tanks what. In the 8 plus years I have played this game, NIN being my main job the entire time, i have met plenty of crappy PLDs that I could own for hate, but then there is the DD to worry about, and when you cant keep your enmity spiked enough to mitigate all the damage they are doing you just cant hold hate and the party is screwed simply by the fact that you have now lost control of the party. And on the gear part, it is STUPID simple to have good gear now that abyssea is around so that is no excuse for anyone who plays a tank job. Four people can get just about ALL the af3+1 seals you want and for the most part that gear is good for every job. Yes the +2 is better but the +1s are nice.

Yes other jobs CAN tank things but there are 2 jobs that are simply BEST SUITED to do so. So i don't see where discussing what other jobs can sort of tank is going to get us.