NeoGAF is really a very small part of gaming, but this is pretty much by design due to the harsh registration process and ease of permabans. I don't really think this makes it a "bubble", in the sense that it's a reasonably representative sample of gaming in general, probably with an enthusiast / dedicated gamer slant simply due to effort of access. League of Legends is hardly underrepresented, with 12 OTs (over 200k posts, which again for GAF is rather impressive) and several threads for different events.
My understanding of "bubble" is a community that is unaware of, and doesn't interact with, the larger world. In this sense, as a gaming community, GAF tends to be a bubble with respect to the rest of the "real world", but not with gaming. Being surprised at someone not knowing who the top LoL player is, in my opinion, demonstrates "being in a bubble" more on the surprised part than on the ignorant part.
I do admit it's really impressive to attrack that kind of viewership numbers, regardless of any comparison, which goes to show how incredibly popular LoL.
I think you're missing the scale of LoL more than anything - more individual people have likely played it this month than, say, have ever played a Halo or Resident Evil or Madden, yet even as an MP-only game its OT count isn't that far from the commercial failure SF5 or the SP-only AA JRPG Persona generals that started long after the most recent mainline Persona released in English.