In my experience, when you give developers an easy way to mangle everything together, a sufficiently large number of developers takes advantage to cause chaos. Sometimes it takes substantially less effort to deal with artificial hurdles than it takes to keep a team disciplined without them.

(brings back memories of one of my earliest web apps where I'd written a template system that on purpose delegated all by basic conditions and looping to the calling script on purpose to enforce separation; and then two of my developers tried to sneak in a new tag to allow them to embed Perl in the templates...)