Kritz beam has yellow particles, it's fairly easy to spot. How is it bad if a med heals better and gets uber faster on midfights and they kill the other med? It incentivizes small ad push instead of stalemating on mid and doing roamer sacs for 10 minutes. Same with calling focus fire, you're constantly trying to check everyone's HP instead of just standing there.
KevinIsPwnI think another big thing to note is how it may not always affect high level play quite as much, but it can make lower level play much faster and focused.