Why have I only heard of maybe 2 of those press release links? It just looks like a lot of paid spam.

It is....it's the result of a paid press release from an low-end PR agency.
A few hundred bucks gets your story listed on literally 100s of sites that are run by the agency, and that almost no-one ever sees.
The list looks impressive, though, and it helps slightly with Google rankings, though Googles algorithms try to exclude this sort of padding.

Pick a link at random, and check it out:
http://www.fox2127.com/story/29524010/nuclear-bunker-data-center-to-partner-with-bitshares

Top ranking on Virginia First/ Fox2127, eh?

How about:
http://wsls.com/story/29524010/nuclear-bunker-data-center-to-partner-with-bitshares
Page not found....

Here's one that works:
http://www.myfoxal.com/story/29524010/nuclear-bunker-data-center-to-partner-with-bitshares