no burning to put it to you in a simple way
1 tank
people lvl PLD to 75
are they going to level sync in dunes for exp? no they will not
so if everyone finished doing PLD how can people make pts? they need a 2nd tanking job
but oh noes SE is retarded and didn't make a 2nd tank job but oh wait we decided to make NIN a good tank job boom the deed is done
also i barely see anyone craft some decent throwing thats why no 1 does nin/rng and DD in pts