It's not just a powerpoint slide. SE literally went out of their way to say that BLU was not intended for parties. Repeatedly saying it over and over during the live letter. Also "progression" of a job does mean how it levels. You get more exp when you kill overworld mobs than regular jobs do. (happy face icon) You get literally the same amount of exp from dungeon mobs as regular jobs would. (normal face icon) And you can't do the roulettes for the bonus exp you get like normal jobs can cause you are locked out. (hence the sad face icon)

That is how the BLU job "progresses," how it "levels."

They then went and said, "oh but wait, if you "party" with other BLUs you have a better chance of getting the spell since the game doesn't roll for each BLU in the party, it just rolls once for the whole party of BLUs." Meaning the more BLUs you have in the party the more BLUs will get the spell, thus making more BLUs with the spell in the game faster. The bad thing is outside of some Dungeons, a party of BLUs have a really hard time bringing down Hard Mode Primals. It doesn't have a battle raise so any BLU that dies is screwed if the skill drops, and It can hardly take a hit even with Mighty Guard. Leaving one or two BLUs to spam White Wind to try and keep the BLU tank alive. Thus it's not designed for party play. Since you can't take a hit tho it's also not designed for solo play in Dungeons and Trials unless you are vastly over leveled than them. Even some things in the carnival hit like a truck and it comes down to can you do the fight without taking a single hit or realizing you can stun or silence things that you can't avoid.