The personal score system is horribly flawed. It's only useful for complete beginners who have no idea how to play Dominion at all. For anyone trying to improve, personal score is incredibly misleading, potentially even to a harmful degree. Personal score entirely ignores various nuances in gameplay and gives players faulty representations of their contribution. For instance, if Alice caps a point while Bob zones away an enemy, Alice gets a higher score than Bob. Personal score teaches that Alice and Bob should've capped together, even though the point could not have been captured at all without someone zoning away the enemy.
The high-MMR Dom community asked Riot to remove personal score quite a long time ago. Supposedly the response was that the system was too heavily ingrained into the game mode to remove without a decent amount of work. The HUD update accidentally removing personal score from the scoreboard was generally considered a fair compromise.