It's all about money.
Riot (finally) changing to share a bit of profit with teams. All sponsors and ads you've seen on broadcasts up to this spring split was money straight into Riot pockets. Teams only got a smidgen of money before from Icon sales, usually just a few thousand dollars for a year. Riot also used to have more stringent policies about how teams could use sponsors logos on jerseys and product, which coupled with the fear of relegation made many teams struggle to secure sponsors.
Teams will revenue so giants such as TSM give a slice that is shared among less popular teams.
The downfall of this is that Riot was able to demand a big up front buy in. Most recently teams paid for a slot in LCS for 2 million and kept it by playing well enough.
Riot now demanded 10 million.
Riot also had the nebulous selection process that let them choose who got in and who was cut out. Optic Gaming got in, rival large organization NV was cut.
They also had a "third party" help analyze the "best" franchising partners.
If you were wondering why a venture capitalist buyer such as an NBA owner was deemed better than an organization backed by a Hollywood venture capitalist backer, it probably boils down to the 3ed party company involved does financial business with NBA owner groups.
In the long run, LCS will be better for the teams who got in because Riot is actually sharing now. Downside is Riot was able to reshape the owner landscape as they saw fit AND demand money to get in so beloved franchises got shafted.
Edit Oh, another plus is a player organization is in the works, like a union or Players Association like sports leagues. This would mean players having more bargaining power for baseline pay and benefits, as well as potentially helping bargain a code of conduct, punishment standards, and an appeal process for punishments.