I think firstly, they're not necessarily grouping it together with more traditional sports - hence the eSports branding of it
Secondly, there is a huge market for it as demonstrated by the number of people who currently watch it both in a competitive setting and a more recreational setting.
I used to be a pretty big gamer and have actually played in some "eSports" games at a fairly low level (qualified online to compete in an in-person qualifier - maybe similar to a lower league team reaching the FA Cup 3rd round? Not really sure) - and it is a competition in the same way as anything like football is... there are huge levels of preparation, tactics, communication, teamwork, individual brilliance, and luck that go into these games and people who like them will appreciate it and people who don't, won't. We can all appreciate a simple looking pass that cuts out 4 opposition players and puts a striker through on goal (not that we see it much!!), whereas my wife only really realises something has happened when a goal is scored - horses for courses.
I don't see it as any different to any sport really, and although I don't really watch any eSports these days I have watched a fair few "world championship" matches live, with serious money on offer. Not everyone has to like everything.