Getting a job to 100 is not equivalent to learning a job nor is playing the pentamelding roulette, you can consider the fact that you can level a job without understanding it as a bad design aspect on squares part and if agree with you but that isn’t the point
Did you level your jobs manually or via macros, if it’s via macros do you understand why your macros work? Do you know the best arrangement for altering your macros as needed? Do you know what every type of condition in expert is and what its priority order is?
There is a lot to crafting beyond “I got it to 100 and bought pentamelded gear” just as just because my combat jobs are all at 100 doesn’t mean I have any idea how to play the jobs in PVP