Leech trick or job swap trick or not, BLU was and still is ridiculously easy to level if you literally just farm enemies above your level (start going Azys Lla for example at lv55 already). Blows my mind how people make a fuss about how certain unorthodox methods allowed people to level their Blue Mage a bit more efficiently, when - and I'm gladly risking a limb here - probably the majority that complains about it levels their combat jobs with Palace of the Dead / Heaven on High on the first few floors, which is arguably as mindbogglingly easy as levelling Blue Mage in general.

This whole conversation imo makes no sense - BLU is easy to level, unorthodox or not and a level skip potion for this job is arguably the most useless thing to add.