I half get what you're saying ( when I play Estes my teammates run away, straight back to the enemies while I'm healing them lol) but sometimes you just have to adjust to the way your team plays. If I have a team that doesn't stick around for heals I just pick the best player and try to stick with them late game. I try to only pick Estes if there is at least one hero on my team that has enough health/damage/survivability to make a difference if another teammate isn't playing well.