I'm going to have to disagree with you here.

For example:

#7—I had written a lot before my computer stopped working.

The same sentence using the past simple:

- I wrote a lot before my computer stopped working, changes the meaning! It implies the computer stopped working at some point in the past, or that you used to write a lot in the past, then your computer stopped working.

Another example:

My father died yesterday. He had a heart attack.

My father died yesterday. He had had a heart attack.

These two are almost identical, but the first implies he definitely died from a heart attack. The second shifts the nuance, that he'd a heart attack and then something else happened.

My father died yesterday. He had had a heart attack. That didn't kill him, a stroke did.

Not sure where you've found your evidence, but the past perfect is used all the time. Sorry...