I think his linguistics background helped him push the boundaries of what people expected from computer programming languages rather; being able to break out of the PL design mindset is part of what made Perl groundbreaking. If I recall correctly, the syntax and semantics of Perl are intertwined to the point that parsing Perl without also evaluating is provably undecidable. From a purely academic standpoint, that sounds like a nightmare, but it's hard to argue that Perl didn't have a significant impact. Many people can learn all the rules and conventional wisdom in a field, but being able to understand the underlying principles well enough to ignore some of them and produce something of value is much more rare.