This is a symptom of the disease. Get more Valor get better gear, get better gear get more Valor. PvP players are trying to get to Valor 60+ so they can wear their ubar gear and they want to get there the fastest way possible. Whats the fastest way? DAMAGE' DAMAGE' DAMAGE !
Why heal anyone? you hardly get any medals for that. Why cap a node? unless it's easy and convenient to add to your total, if you have to work for and might die forget it.
It's not the scoreboard it's the Valor for gear disease that brings this behavior. It's no different in PvE raiding, get the best gear as fast as you can at all costs.
Look at it this way, once you get to 50 and valor 60+ you can find a good PvP guild, make a premade and win, win, win. Because you will have out geared your opponents and they wont stand a chance, till either they get geared or the next patch adds higher gear.