'Stupid' seems a little harsh. I suppose much depends on the intended meaning.
1. It's as much X as Y.
If the speaker intends an adjustment to some previous statement, it's fine. In some of these googles, for instance –
http://www.google.co.uk/search?q=%22...&start=30&sa=N
– you find the parallel noun structure, e.g.
2. It is as much poetry as prose.
Here, the speaker is correcting an implied assessment: "you might describe it as prose, but in fact, it would be just as valid to describe it as poetry/it contains just as much poetry".
Similarly,
3. It's as much blues as country, with a raw, almost-rock energy...
This 'corrective' intent is also possible with the adjectival version:
4. It's not easy to describe a greenway because it is as much conceptual as concrete...
Again, an adjustment: "you might try to describe a greenway in concrete terms, but in fact, it would be just as valid to describe it in conceptual terms/it has just as much of a conceptual element to it".
But if the speaker intends simply to express equivalency, with the similar construction 'it's as X as it's Y', e.g.
5. It's as broad as it's long.
– there's no need for 'much'. For example:
6. [Scenario: a cricket ball is discovered among the headmaster's broken cucumber frames.]
"Q Minor! Come here, boy!"
"What, sir, me, sir?"
"Yes, sir, you, sir! Now then. What is the meaning of this outrage?"
"Outrage, sir?"
"Don't come the innocent with me, sir. I clearly saw you throw that cricket ball over the headmaster's wall."
"Not me, sir. I was playing football with P Major. Isn't that right, P?"
"Don't lie to me, boy! I saw you with my own eyes!"
"With all due respect, sir, your eyesight isn't as good as it was...And from such a distance – "
"Sir, you are as impertinent as you are irresponsible! Bend over this instant!"
etc etc
Here, the speaker isn't adjusting or correcting an assessment: rather, he's saying 'we already knew you were irresponsible, because of your behaviour with the cricket ball; and now we find that you are equally impertinent!"
This 'equivalency' is already expressed by 'as X as it's Y'; so the 'much' is redundant.
But it seems fairly venial to me.
MrP