There is no city limit or highway limit. You CAN run as fast as your car lets you, and the WHM car goes slower. I award you no points, and everyone is now dumber for reading your post.
6 other jobs can give MP to party members. True or false? I don't care if you, as a RDM, would RATHER not. They can, and if they decide not give up 20 percent of their MP in your hypothetical situation of an immanent wipe, they are bad players. And by the time that immanent wipe comes for most parties, it's late in the fight, where the healers have would have ALREADY listened to a minute or a minute and a half of refresh, which more that most healers ever hear now, even during progression.
Again, I care about balanced healers in all content. You're obviously on the forums arguing trying to make yourself feel better.