It's an interesting mechanic; you can use it to allow strategic use of your mp in game. Of course, the trade off would be less mp for other things, kind of like turning someone into a berserker for a couple turns by sapping their mp.
If MP is also the resource used for casting skills in the first place, it becomes a very weird mechanic because you have one resource trying to gate two entirely separate things at once (extra effects and skill use). I've never seen this implemented effectively, except for games like Race for the Galaxy where you are making an either/or decision with your cards (which are the resource).
However, this could be a good mechanic for warrior-type characters that don't use MP as the resource for skill use.
Waiting on approval on my One Map Challenge game, which I made to get a feel for RPG Maker. I was able to complete it before MZ's release, now I can focus fully on the MZ game I want to make. I'm excited, ya'll.
Hey I'm new the RPG Maker forms as well and was having the same problem you are with needing 30 post or 30 threads we must complete. Maybe we could help each other out? Why you on the forms what is your goal?