I totally understand that and absolutely agree that less is more in the context of non-geo interest in geology. However, my concern is that essentially you did not answer the question: why is there no extensive volcanism in the Himalayas, although this particular collision is the most intense (given the side of the Karakorum-Himalaya chain). Thickness of the crust is not an answer since that crust has been accreted gradually and there was a time when basalt was subducted and the crust was not that thick. Metamorphism would be too convenient an answer, not necessarily backed by facts. Keep on the good work!