A Stack Exchange site for Tor (https://tor.stackexchange.com/) exists. Could that site and this one not be merged, since they overlap greatly?
Proposal: Deep Web
The Deep Web is much greater than just Tor. They should not be merged.
It's like saying we already have a SE for Wordpress so we don't need a SE about CMS in general. That's simply not how it works.
You got other networks like I2P, Freenet, Morphmix, JAP and more.