It is a fallacious nerd narrative that LEOs want super powers to keep track of what kind of anime porn you watch. They don't care. The day-in day-out of LEOs involves crimes so banal (embezzlement, narcotics, counterfeiting, &c) that they don't catch your attention.
What's changing is that technologies that dramatically raise the cost of investigating those crimes are now the default. As a civil libertarian, I'm glad of that. But as a citizen and a counterparty to the social contract, I can appreciate the underlying concern.
The thing you "just know" is false. They care a lot more about child pornography (which happens a lot more than you appear to think it does) than you think they do.
When they try to outlaw full disk encryption to increase their chances of catching child pornographers, let's all share outrage together. Until then, try opening your mind a little bit to LEO's concerns. They have real ones.