The comparison with MTV is insightful. But what do you see as the equivalent of "dozens of access/consumption points" in sports? (I'm not following any organized sports)
#1 is that ESPN doesn't own the rights to air all sports (1), they have rights to certain events or leagues to air games on certain nights. For example, ESPN only airs 1 NFL football game per week, which is on Monday night. CBS, Fox, & NBC air games (which are subject to localized markets) on Sundays at various times.
Another example, DirectTV (a satellite provider) offers a content package called NFL Sunday Ticket which gives subscribers the ability to stream any game live in any market (which is in many NFL fans opinion, the superior option).
... which brings another note to the parent topic - I would assert Sports (specifically the individual sport leagues) are effectively monopolies. The NBA is the professional basketball league in the USA. Its largely considered the best league in the world. It's product is very difficult to replicate. So those specific "properties" will continue to try to maximize their value as well as grow their audiences - and its not like you know Seinfeld is super popular so you can just write a new show and call it Friends.
2. When I was growing up, Sports highlights were ESPN's bread and butter. You couldn't watch every game the day or weekend before, so you watched ESPN that morning or night to see what happened and the spectacular plays. Well, now twitter or youtube or reddit are better sources of highlights than ESPN. They are on demand, close to real time, and (IMO) often higher quality.
3. Lastly, the "analysis" and ancillary Sports content that ESPN works hard at, is very competitive now. There are great podcasts and blogs for every sport and most teams. Those channels can be accessed almost anywhere - and they are often more "targeted" than what ESPN is offering.
For example, I am a Memphis Grizzlies NBA fan. Let's equate that to I'm an Enterprise SaaS fan. Well, r/MemphisGrizzlies is kind of like Jason Lemkin's SaaStr - a site dedicated primarily to my specific niche. ESPN would be more like TechCrunch at large.
1: https://en.wikipedia.org/wiki/List_of_ESPN_sports_properties
Sports subreddits are a prime example of how hardcore fans are finding more focused and higher quality venues to follow sports. The comments on r/NFL or r/NBA seem to be of a much higher quality than those on espn.com. As you said, over time it means fans just use those sites as their sports portal rather than espn.com or Sportscenter.