Are there any well-known academics who have turned against their own
academic community, for it being too complex and full of jargon?

The most famous case is the one of Alan Sokal (Professor at NYU) and
Jean Bricmont (Professor at the University of Louvain in Belgium)/
They co-wrote a book criticizing some famous academics whom they
condidered imposters. Those academics were Jacques Lacan, Julia
Kristeva, Gilles Deleuze, Jacques Derrida and others, French
philosphers who are very well known in the US but who used
mathematical concepts and concepts derived from physics to bolster
their philosophical arguments. They used a lot of incomprehensible
jargon. Bricmont, himself a nuclear physicist said it was non sense.
Bricmont and Sokal's book is called Impostures Intellectuelles
(Editions Odile Jacob, France)