Thank you Riot for letting us know mastery in loading screen
To me it's a great idea because you can show off your mastery and let the opponents know your level of knowledge of the champion, I don't understand why people complain but I say its a great idea and motivation to further increase your mastery because who the fuck even goes to your profile to see your masteries? If you don't want to show your mastery then make an option to hide it but don't remove it for those who want to show it off.