All I have to say is that although the edginess is definitely cringy, it doesn't seem unusual considering that the mods on this tumblr page are in their teens and teenagers do stupid shit.
I think it's common for teenagers, especially those who lack emotional maturity to do edgy things such as sending gore, there's also an extra layer of dissonance if you take into the fact that there's a group culture involved (by sending gore, in a group where everyone else is sending gore it takes some of the responsibility off you), keeping in mind the internet causes distance, and an emotional separation, so people will do things online that they wouldn't consider doing in real life.
These kids, if they do know each other in real life, probably consider themselves to be misfits, and try to purposely do things like this in order to separate themselves from society and societies norms in order to better fit into this label.
I don't know if 4chan is still as popular as it has been in the past, but the culture involved as being as shocking as possible on sites such as 4chan and ED have probably also had an influence on their decision to send gore.
These children most likely come from a middle-upper middle class home, but due to their delay in emotional development, possibly due to psychological issues such as depression, seek out social interaction online with people of similar emotional maturity.