I agree with what you're saying (aside from comparing that really awful episode to Shadowrun), but that's not what went on in Stranger Things. It was just....

From the very first episode, I asked if they had changed writers because the dialogue was so different, so bad, and so predictable--all of which only grew worse with each passing episode. And when each character had their turn to explain who they are and how they feel, it fit the same exact pattern every time. It was just really bad writing.

All that said, I don't think the last season was terrible. I expected it to be a lot worse than it was. The actual plot and ending of the story, I thought were perfectly mediocre and fine. It was ruined by the dialogue.