I wrote this bit, but then saw your post. Just gonna tag it on to you since it is related.

Answer: Not going to happen.

Valve has a sweet spot with CS. A thriving competitive scene that they have never had to directly support. This brings players, revenue, sponsors, and most importantly: money. Historically, Valve never had to lift a finger to maintain this network of competitive platforms. LANs, tournaments, casting, league admins, maintenance, and people that handle disputes. It all existed without Valve's help.

Valve changed this in CS:GO. They provided the basic fundamentals that modern gamers expected. A matchmaking service, various game modes, and community servers. All paid for and maintained by Valve. Their game was growing, but not fast enough by their standards. So, they added skins as a revenue platform, injected 750k of tournament money into the game, and created updates by listening to player feedback.

Now we have a massive playerbase that is growing by the day. 3rd party tournaments have never been stronger; providing prizepools that rival Valve's. Valve doesn't have to provide: admins to deal with leagues, disputes, cases of cheating in matches, maintenance/planning/logistics of running a league. It's just not necessary. Not only are those things covered by companies such as ESEA or ESL, one could argue that those companies do things much better than Valve ever could.

This is a good thing. I will briefly explain why. If Valve hadn't done all of those things I have no doubt there'd still be a competitive scene in CS:GO. Why? Because of our system of 3rd party league and tournaments. When the game is dying (this will happen eventually,) and Valve no longer finds support for the game lucrative we will still have a network of 3rd part systems that will keep the game alive.

Valve is sacrificing revenue from such a league for the fact they don't have to support all the things that come with a league. There is just so much bullshit that comes from running a league/ladder that it's not worth it in CS:GO. Maybe in dota2 there wasn't the infrastructure to rely on such systems and the ones that exist today simply developed over time, but CS has always been run by 3rd party systems. And those 3rd parties generally know what they're doing.

This creates a healthy, thriving community where players have choice on how they want to play the game. It is a system of graduation, where one plays enough MM and then decides they want to compete in the game. It's simple. It's easy. It's low cost. It works. Why change?