I think my ISFJ mother qualifies as a person who happened to be extremely unhealthy for valid reasons. She had a combination of constant anxiety, incredibly low self-esteem, an unhappy childhood, issues with divorce... you know, the whole enchilada. And not to mention, I had my world crashing on me, including the constant marital & financial problems my INTP father caused. What didn't help was how she started taking on everyone's problems as hers, and my own rejection of outside support caused my mom to become even more intrusive. I simply needed massive breathing space when I'm at my worst, and the involvement of other people drains away my energy, or stirs more trouble and distress.
There was too much sharing, and not enough trust in my home-life. My thoughts were the only things I could exercise control over, without having it to be "we". So it felt like she was cutting my entire life-support when she micro-monitored my every mood, idea, and decision to make sure everyone she knew was "ok" with them. My ISFJ sister and ESTP brother had an easier time ignoring, or adapting to her ways than I did. I'm a special case in requiring high amounts of independence and solitude at a very young age. This behavior seemed unusual for my ISFJ mom and by the standards of her experiences, as she shared everything with her family. We both didn't know how to effectively communicate our needs and wants to work together.
Yeah, it was a rather dysfunctional family. And everyone had a role in it. Type (or personality), more or less, influenced those decisions within that role. No one was any more responsible for creating those family burdens than the next participant.