Can we just instigate a rule for pros that a champion can only be player one time in any series. This would improve the strategy of pick ban and force diversity and adaptability in pro games as well as leaving riot to balance around solo que because op champs would be less impactful in LCS.
That improves diversity, sure... but at the cost of hamstringing the players. That's akin to saying "We can't balance around the fact people are picking this one specific hero, so now we're just taking him off the board entirely until the next series, so you better make your one chance with him count." You don't hamstring players for sake of the developers in an eSport. The only actually viable options are Developers balancing the options on the table so that options on the table change for eSports, or they don't balance for eSports at all.
Regardless of your stance on pro play and the balancing thereof and its impact on the common playerbase, Riot has already picked their side and so the second option there isn't actually an option.
