I agree with this. I think this golden age of television that we are in is only helped by killing shows before they lose what makes them special. Netflix’ own Stranger Things is a great example of this. The first season was amazing, the second one really good, while the third one really feels like it’s time to wrap things up.
Another example of a show that ran way too long is Orange is the New Black. Amazing for a couple of seasons and then it just fell apart. IMHO, off course.