You're comparing completely two different Platforms, audiences and genres. If they will show naagin and stuff in digital platforms surely it will be disaster. Vice versa if mature content is made for tv audience, nobody will watch it.
If naagin won't get any rating something similar will get ratings. It's all about audience bro. If naagin1 would've been failed makers wouldn't have made naagin2. The thing is our mass audience likes it,Ratings goes up, Both channel and producers gets good money and the cycle continues for seasons and seasons. That's how it is working in tv over the years. Earlier it was Saas Bahu, Now it is supernatural tv shows.
Aside, you just tell me would you ever be able to stop someone from your family to stop watching this shows?