1) Yes, it does give more MP, and
2) there is no "true" SMN playstyle. You're welcome to play however you want,
Most of what Dallas says is nonsense, but I'm sorry, SMN cannot recover the amount of MP Myrkr can give through refresh and Siphon alone. These are not "lies." I challenge you to recover 1500 MP in less than 2 minutes without using ethers. You can't do it.
Even if it didn't give more MP (it does), that's not the point. The point is it allows both you and your avatar to fight continously, without running out of MP, which is the whole point of the strategy.