To this day, I really cannot empathize with "having a team." I get that it comes off as neckbeardy or holier than thou, but it just seems like arbitrary tribalism - maybe because I moved around a lot as a kid(from BIG SPORT cities, too! Green Bay to Houston to San Francisco), but I never really understood why people prefer "their team" (other than the obvious, logical reason). Maybe better - I can't empathize.
This isn't for lack of trying - when I grew up my dad and his friends would yell at the TV. That looks fun! They're so excited and engaged, why can't I feel that for a sport? Genuine emotional response to whatever "our team" is doing? I mean it's not like my life is empty without it but I've always wondered why others can feel strongly enough to shout at a TV but I never could. Not for sports, esports, not even when a couple of kids from my class were on ninja warrior.
Some people tend to like specific players which shuffles their teams around, sometimes from year to year. I think this has been a change over the years - each league wants more viewership on all their games, not just the bigger markets. So you can drive that by 1) running and promoting fantasy games and 2) promoting individual players.
If you play fantasy football you end up shouting at the TV for games you normally wouldn't care about. But then you end up liking some of these players so you kind of root for their team too.
Put some money on a game or try fantasy sports if you like sports but don't have any horses. It can be addicting but it's fun, especially in an office pool. I would have never watched Houston Texan games but I had Hopkins & Fuller and it was cool watching DeShaun Watson emerge from the backup role (really unfortunate he got knocked out of the season recently though) and they had some unbelievable games.
Major sporting organizations (MLB, NFL, NBA, NHL, etc...) are very good at selling stories of players/teams and having people emotionally connect with players/teams at that level. This is what leads to favorite players which can lead to favorite teams.
Another aspect is region. For example, I've grown up in Seattle since I was a toddler. Everyone around me is a Seahawks fan. I am a Seahawks fan. It'd be too much to follow multiple teams for me, but some do.
This gives me something in common with those around me, and having team spirit and dressing up on Sundays is fun. Hanging out with friends on Sundays, watching football, and shooting the shit is a lot of fun and sometimes the only time we can all make to see each other as we get older and our lives drift in their different directions. That bit was a little off tangent but it does help illustrate why someone may like sports.
I'll agree that learning the rules really helps. When you're watching two different teams line up against each other, attempting to read what the other team is trying to do and executing against it in real time is exhilarating! There are several aspects of the game that have to be accounted for on every single play. It's a mental, physical, and emotional game.
Hope this helps you (or any reader) understand why someone may enjoy to watch sports. Go Hawks! :)
Agreed, always reminds me of this classic Mitchell & Webb sketch: https://www.youtube.com/watch?v=xN1WN0YMWZU
Similarly, while I understand why (American) football can look like 11 armored clowns randomly bashing into each other, it is arguably the most interesting and strategic game on offer by the time you understand the rules, the why of those rules, and the resulting strategies, metastrategies, statictics, etc. Baseball is also more interesting when you understand more of the whys of what is going on than just "Man hit ball with stick and run fast".
Of course there's no great virtue per se in loving to watch sports, so I'm not advocating that anybody seek this out, but if you are interested in what all the fuss is about, I recommend learning more about the sports and the rules and the second-order effects of the rules and such before writing them off. Unfortunately, I do not have any references; I did it the long, slow, hard way.
(Contrariwise, while soccer is fun to play, learning more about it has still left me pretty cold to the sport.)