Perec and Benabou

After reading the rest of The Void and "Rule and Constraint" by Marcel Benabou. I found a quote from Benabou's article that stood out to me. "For four centuries, we have been very comfortable...for instance, that an alexandrine has twelve syllables, that the sonnet has fourteen lines, whose rhymes are disposed according to a very precise order." When reading this quote I immediately thought of The Void. Perec did just the opposite, it seems, than the "rules" made int he past four centuries. He did this, obviously by taking the vowel "e" out of his entire book. When reading Rule and Constraint I thought it was very interesting how it corresponded so well with Perec's book. One thing that really got me wondering was in Benabou's reading he said constraints give deeper literary expression. How can that be? A constraint is in a way holding you back? How can a constraint allow for further expression if it's holding you back?