Harrington's "M"... still a relevant and good concept?

[CianCrillz]

I have read HoH recently and he talks a about M "blinds divided by stack" and reading into another topic about Harrington's WPT win someone mentioned

"I'm not surprised. Most of the tournament hotshots ridicule his books and dismiss his play as "weak-tight". Just look at how obsolete, in the view of some, the whole concept of M has become."


I am just wondering what is the thinking behind M being now obsolete. Thanks.