Not gonna play them if they include their launcher after game is started from Steam lol.

Battle.net launcher can literally be closed after the game is running. It even has a setting to automatically do so. Why would they pull this sort of bullshit, I have no idea

Each time battle net launcher opens,it displays a popup banner for cosmetics, warcraft stuff, overwatch stuff etc. They get free ads in your eyeballs.

No way they will let it go. It will be steam -> battle.net -> game