No product is going to cure people of anything and certainly no commercial company has that kind of capability.
"And so the problem remained; lots of the people were mean, and most of them were miserable, even the ones with digital watches."
For 'digital watch' replace with iPhone, iPad, Playstation etc
I read the line you quoted as saying designers and developers should build things in ways that don't make life worse. We can't "cure people", but we can make their lives better by considering their needs. This is true for everyone, but especially more vulnerable people.
Taking Monzo as an example, they make it very easy to freeze your card if you lose by enabling a user to do it via their app. And they enable a user to unfreeze their card if they find it again. Other banks make you telephone a call centre, go through automated menus, and speak to someone to cancel the card and then you have to wait days (or weeks..) to get a new one. Someone who has lost their bank card is already likely to be anxious, so Monzo have made their life a little better. It's good that they think about these things rather than just copying the other banks.
And so of course we should not try to build software that takes vulnerability into account? Just because you cannot cure something doesn't mean you cannot help.
I applaud Monzo for this effort, they continue to prove that moving to them was a good choice.