What he said is that some people can not get into prog because they can not understand the rhythm. How does that translate into prog is just about numbers?
What he really said if you actually look at how he phrased it was that people who don't completely understand the rhythms aren't allowed to have an opinion on whether they like it or not. To that I say "shut the fuck up".
Honestly, what he said is just like when some newb comes on here and says "if you don't like this thing that I like, that just means you don't understand it". That always annoys the shit out of me. Professionals on this level should really be above that. THAT'S my main problem with this quote. I'm not doubting anything about the science here, that's all fine. But how this guy says it is just bad and condescending.
Well for one thing, it's very likely this comes from him feeling the need to defend himself from all the endless accusations and assumptions about groove and whatnot. Also, he's not saying they're not allowed to have an opinion, but if they're going to write something off before they understand it, then it's going to be a fairly ignorant opinion. And really, the only way I could possibly imagine his post seeming offensive, is if you think he's talking about you.
I'm not sure what you mean about professionalism here, but isn't this that how it works: if I don't like this thing you like, then I simply don't understand it in the same way as YOU do. I might have a conception about why I think some people like it, and I can describe why I don't like it. But really, I shouldn't be pretending that I "understand" it.
I dunno, lets bring up say, rap music. I can appreciate aspects of it, the writing and wordplay, the rhythm, but as a whole, I don't understand it on the level of those who are passionate about it. I mean, lets say there's a generic pop song that I'm describing and writing off, if I think I understand it (and the emotional responses of all the people who feel something from it) then I'm kind of arrogantly invalidating the experiences of those who connect with it on an emotional level beyond the conceptual level that I have.
And then there's the inversion of this (the side MM is defending) where people write things off because they've formulated a conception after they didn't feel anything from it (not musical, too technical etc.) and then assume they've sufficiently accurately described the situation all the while completely invalidating the views of those that would claim otherwise.