Overwatch as a "watchable sport" was never going to happen. Too many characters, too many objectives, too many abilities, too many characters to track, nothing permanent for viewers to latch on to, too little downtime/breathing room, everything is unimportant, and way too many character v character matchups/counters to keep track of.
There's also a very long TTK and a very low skill ceiling compared to other "pro" games. It's too complex for normies and too simple for "pro" game fans - so the audience basically doesn't exist. Making it a league also means there are way too many games and makes following it a much longer commitment than many people want to sign up for. The games go on for way too fucking long and aren't spaced apart in scheduling (with most games being on Friday, Saturday, or Sunday) and are just rapid fire back to back nonstop.
This is something that even the NFL doesn't do (which obviously has way more people that would watch every single game) and even if you were to ardently always watch "your" team - there's a lot of garbage to sit through to do so in terms of schedule.
It's like a really bad movie in terms of watchability - a lot of stuff is happening, most of it incomprehensible, and if you think about it for a minute you'll realize none of it matters.
