Why is it not allowed to hide certain champions from your profile?

Showing off your highest mastery ranks in profile was supposed to be a privilege, not something that can be even used against you (i.e. target banning your mains). This seriously needs to be optional, like having "Hide/Display Mastery Rank In Profile" checkbox for each champion or something.

And there are more reasons for that. Some champions get completely relaunched, people switch mains. In my case, I used to play Evelynn almost exclusively, but after her relaunch I never touch her anymore. Yet my profile still screams "Evelynn main" and even resets back to Evelynn background if I stop playing for a day or two. Not only it would take an insane amount of time to match the mastery score I have on Evelynn, but I also have to waste blue essense on mastery level and I barely even earn blue essense anymore.

Worst of all, when asked to reset my mastery level for a valid reason (zero experience on the new version of a champion) Riot support told me it's against their policy to do so.