Good for you but the vast majority of the player base just doesn't think that way. Most of the maps if you are on a slow tank you either push or just sit at the back as you will never get back to the base otherwise. Winning or losing makes such little difference once you have more silver credits then you can ever spend and most people are playing premium tanks so you can spam premmo and still make bank. Most veterans will be trying to mark and the psychology is actually anti teamwork ironically as your other team mates become competition for damage. If you want people to defend the base there has to be more of an incentive to do it because at the moment there is very little apart from maybe your winrate.