It just means the garbage will be submitted by people with $100. There's plenty of junk on the iOS App Store which has the same developer license required.
The OP said "Let's say I wan't to host it myself". So his pricing is right.
And the new appstore doesn't stop anyone from hosting their OSS on github - even for Macs. The appstore is for the average user; github is for the better than average programmer.
Have the terms changed so radically from the mobile store? At least there licenses like the GPL are incompatible with the extra restrictions that Apple places on the software it distributes, causing software to be removed or refused.
If you're in any way serious about your Mac-based product, you'd probably want to be part of developer programme even if you don't care about the app store. (for testing with prerelease OS versions, etc.)
$99/year
Hm ..