That's not a flaw in "bitcoin", that's a flaw in the human race.

There will always be people in the world that give bad advice on any topic.  There will also always be people in the world that are foolish enough to take bad advice without considering the consequences.

In reality, maintaining control of your private keys is a perfectly valid choice for many people, and trusting someone else with control of the private keys can occasionally be the better choice for others.

However, I'd suggest that if you need to trust someone else with your private keys, then you'll want to make sure that you choose a business that is well regulated, audited, and insured.