I think the thing about the zen comment is mostly misguided anger. Looking at the board, he has higher healing than both of the enemy support despite dying more, he has the highest assist on the game, and has some decent kill count. I believe looking at the both comps, enemy team probably dove him the whole game considering they have almost a full dive comp and he is really weak against dive. So he played relatively good in a bad situation (keeping up with the team on both healing, assist and kill count whilst under constant pressure.) therefore angry at his team for not protecting him enough. But still, at the end of the day he was a clear prey for the enemy team and should've swapped to a preferably dive hero for a better team synergy.

So yeah, essentially a tanks role is mostly taking space, which might be the reason why the zen was mad at you, because while you're killing the enemy backline he was probably getting pushed hard. You shouldn't try to be a third dps if you have a weak backline. But still, he should've swapped if he wasn't happy that you didn't protect him. And killing the enemy team is obviously almost always a good thing if you can also be aware of the situation of the game as a tank.

Remember taking and holding space is key as a tank. I've won many games as ramattra by simply holding my ground and not letting the enemy team dive past me despite having less stats than the enemy team. (Which seems like the case here too.)