No its not, because not only new people dont understand it, but unlike just about everything in the game, its not intuitive to use. It clashes against the current game design massively.
That is what Sym mains have wanted for years, yes. A functional hero that is not a team TP slave.
Who? Just about every hero works at a base level without needing hyper-specific actions from their whole team. Even Zenyatta was given a kick to peel for himself.
Team TP is simply anathema to the current game.
Both heroes are currently in a better state that Sym. In fact Mei got some compensation for the loss of freeze. Sym got massive damage nerfs for a slightly faster kit.
She is still garbage. Like even if people work with you, there is nothing she can do that other doesnt do better. She isnt a generalist either, she is just a master of nothing except team TP slaving.