It's not just that people don't want to hurt your feelings. (I kind of want to say "It's the Internet. No one cares about your feelings.") A decent part of what's going on is that people are interacting less with content posted online, and with each other.
There's so much content out there these days that people can just move on to the next piece of media without any thought to what they just saw. No thought given to the fact that another person on the other side of the screen made whatever content they just interacted with. Because there's always something else, and if [general] you stop posting for whatever reason, there's now something else to fill the void. I can think of many examples of this just in the content creators I follow.
You could maybe get some more reviews by saying that you're open to them, or asking your readers specific questions about each chapter. what you're looking for in particular from responses. You say you want to be "ripped to shreds", but....do you really? No one can be really sure how an author will react these days, which is why they don't comment. There's a chance that their perfectly innocent comment or honestly helpful concrit will get lambasted elsewhere.
I think--and this isn't meant to be a negative, just the truth--that your story is very niche. A reader needs to be familiar with both Fairy Tail and Digimon Fusion, which is one of the least popular seasons of Digimon. It's what TheCouchEffect said: writing something popular gets you more interaction. The farther away from popular that you get, the more difficult it will be to find readers.