Honestly speaking, there are few reasons behind that. There’s a universal code that you don’t accuse/question/offend the people who are protecting you— people because of who you are alive and resting peacefully. I know this is kind of absurd but that’s how things are; that’s how most of the people think everywhere. And if that’s not the mentality, the mainstream media makes sure you have it over the period.
There are popular news channels, platforms and journalists who are hyper-nationalists in their views and presentations (maybe that’s how they are or they are just blatantly trying to win mass audiences’ praise, given we are all very touchy about army). They are always pro-army. They have made this notion that Army cannot be wrong—and this has become an accepted, widespread perception. Whoever thinks otherwise, however justified their arguments are, is termed as anti-nationals and receives widespread condemnation.
Same thing is with politician. They know the population is very touchy and sensitive regarding the army. They exploit this fact to do vote bank politics. Whenever someone speaks against the soldiers, they attack them to appeal the voters.
So yeah, these are some complex reasons why it’s a hushed offence to question own army.Every democracy should question anyone and everyone when required—that’s what democracy is all about. But again, this should be done within the limits. We all can question others without the need of throwing allegations and hurling abuses.