I know it's made by tropers and everything and I'm likely to get a lot of flak for this, but having read a few blogs and the entirety of the trope page, I must say that this entire series is rather disappointing.
It feels like the contributors tried to do too much, too fast. With the core mythos, things were revealed one at a time. From Marble Hornets, we got the Slender Man, then our first proxy, then Everyman HYBRID
got the Rake. And that's as far as the original mythos has gone, really. Other than more proxies, nothing else has been introduced. Here, not only do we get upwards of 15 new creatures, they're all introduced simultaneously with little lead up.
Slender Man works because he was built up years and years before any series was created for him.
There are some who think Slendy is only scary because we don't know why he does things. That is not true. It is also because we don't know where he comes from, what he's made of, or how he is capable of doing anything. We don't know enough about him to be able to trust him, and the only things we do know make him untrustworthy. That is why he is able to be feared.
With the creatures in the Fear Mythos, we are told straight up what creatures are made of, where all of them come from, what they can do, and how they are able to do it. There's no air of mystery about them, other than why they do things, and that alone isn't scary.
These things also do not appeal to the same things Slendy does. Slendy seems familiar to us. We've all seen a tall, bald, thin man in a suit at least once in our lives. The fact that he has such a common-looking appearance causes us to think back, trying to remember if that man had a face or not, and makes us question. The Fears are so far off from anything ordinary that they're not scary. Proxies are even more familiar, being regular people, occasionally in masks. We fear them because we have seen things like this before in normal situations, and to see them twisted into something strange ignites some kind of fear in us.
The reason we fear the Rake is because we don't know anything about him. He appeared from nowhere, he's pissed off, and he's feral. That's enough to frighten us.
Keep in mind that I am in no way insulting the writers of the Fear Mythos with this review. I only mean to share my thoughts about the creation of the Fears themselves.