I don't really agree with blocking/mis-reporting people like that, I'm a level 135 and I always do my best to win every game I play. I generally have the top score in about 3/4 of the games I play, it would upset me to know that I'm being reported wrongly just because of my skill level regardless of how I play. I always support the team from outside the garden if I'm a zombie and pick off troublsome plants that are harassing the group, or I flank around and wipe out any Cacti that are bombarding the hill with drones as well. When things are safe, I enter the hill and capture it, retreating if needed when the plants respawn.
As a plant I always stay near the hill, if the number of zombies outnumbers the plants in the hill I'll charge in at my own peril to make sure they don't gain any progress on their capture bar. If the zombies are coming heavily I'll take down the teleporter and hold the area until either the zombies find the base and I have to go back for support or they give up and stop going for it.
There are other ways to do things besides just blindly running to your death 30 times a game, though I do completely agree that players that ignore the objectives completely need to get their heads out of their collective butts. Such as the idiots who just camp the Flax cannons on the mega flower map while there are a ton of zombies inside taking down the flower... Come on people, there comes a time when you need to HELP your team.