Usually, the people who say such things confuse 'object-orientedness',
which is a programming methodology, with one or more
implementations of that methodology.
Perl is not C++ or Java, of course (which are the two
languages that are most often touted as the examples of 'true'
object-oriented languages by the naysayers), so it seems unreasonable
to assume that Perl should follow one or the other's ideas
of what object-orientedness is. I suppose that Eiffel enthusiasts
could feel that C++ doesn't support design-by-contract natively,
and so isn't a 'real' object-oriented language, either.
Just rest assured that despite people's claims that
"Perl's just a scripting language", there are many of us
who develop object-oriented Perl every day.