I can agree with the reliability of Java, but is there a good framework. Having used Java-Play and Python-Django I would say that Django comes with more add better integrated batteries. For a startup, development speed is probably more important. Later you can add microservices in Java if you like.
Well, wouldn’t we have to ask Mark why he chose Perl, then PHP, back in the day? I suspect it’s because they were high on the GTD spectrum.