I feel they should have had this 2 years ago when I started. Hero mastery seem like a pointless addition to the game. My reason is simple right now mastery only gives points to hero they play , so more they play the better mastery. Outside really showing you play the specific hero 1000 times mastery completely pointless because rank tier is a better gauge on a person skill level.
Right now skill doesn’t really exist any noob I feel can hit PoA /VG if they get carried enough especially with influx of ton of Bing Bong players skill has definitely become much more diluted. I felt if they implemented this before 5v5 and/or when blitz/BR was introduced it might actually meant something.
2 . There are no real rewards that we get from mastery expect perhaps pride that you spam a single hero , which now means nothing.