No sources are actually blanket "banned". Some exceptionally bad ones like the Daily Mail are "deprecated", but that does not mean it can't be used anywhere ever. For your edification: https://en.wikipedia.org/wiki/Wikipedia:Reliable_sources/Per... (there's a legend at the bottom)
They are banned. Search your list for "blacklist". Note that the blacklisted sources are only on one side of the political spectrum -- not one thing on the other side got blacklisted.
Oh, you meant Breitbart and Infowars? Those can still be used, but require whitelisting; so still not a ban. You can read the linked discussions for more information. Not gonna rehash and spell it all out for you here. I wouldn't say two instances are a pattern of anything, but going by your logic, guess that side of the spectrum just has more history of spam and persistent abuse on the English Wikipedia.