[Notice] Big Foot Glitch Abuse

Then where do glitches come from?

Glitches are unplanned interaction of code. Imagine if jump down being present in the data made it impossible to jump off of a rope while pressing down (rofl)-- that would be a glitch. This is a mere mistake of forgetting to set a certain variable in the monster's data.

I love how they say they're working to fix it when the solution is so simple/clear.

Just a patch, right? Speculation is that the "Server Maintenance" are done in preparation for a patch, and we did just have one, right? I'd say a patch to fix the issue will be coming, at the very least, before when the next content patch was planned to be released.