Poor performance of the single implementation.
A single implementation.
Leaky ref counted GC, but 'luckily' the syntax for references is so clunky that nobody does anything complicated enough that it really matters.
Bolted on object oriented features that never got the love they needed at a time when oo languages were sweeping the world.
Most of the wizards decamping to a new language (Perl6) that was 'developed' for years without an actual implementation to keep them grounded.
That made me laugh. Unlike actually working with Perl references, which made me want to cry.