A lot of academics are bad writers, philosophers included. In my opinion, philosophy is actually far from the worst offender. If you read philosophers who are good at writing and actually have something to say (e.g. Bertrand Russell, Thomas Nagel, Susan Wolf) they can be short and illuminating.

By the way, there's a big divide between continental (European) and analytic (Anglosphere) philosophy. The Calvin and Hobbes joke is poking fun at postmodern continental philosophy (or literary criticism or gender studies) but most analytic philosophy is not like that.

Or there is a lot of nuance and long history of arguments behind concepts like free will, consciousness, realism, emergence. You can't simplify the arguments without glossing over a lot of detail. Philosophers prattle on because they're responding to all that. They're aware of the various objections to their position.