The problem is not that it uses whitespace, it's that the amount of whitespace has semantic meaning.

It doesn't quite change the semantic meaning, but Perl thinks the programmer uses the amount of whitespace to have different semantic meaning:

$ perl -wcle 'print("foo")'      # 0 spaces
-e syntax OK
$ perl -wcle 'print ("foo")'     # 1 space
print (...) interpreted as function at -e line 1.
-e syntax OK
$ perl -wcle 'print  ("foo")'    # 2 spaces
-e syntax OK
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