So obviously bad advice, but the reason is that to declare bankruptcy you have to convince a judge to do it. You might have trouble with that using this terrible plan.
I was offering debt advice to a young person recently in the UK.
They had gone to a UK debt management company that seeks to compound your debt by asking your creditors to accept an Individual Voluntary Agreement where you agree to pay back a certain amount per month for a fixed period and then get it written off. In practice it affects your credit rating like bankruptcy. They were advised by that company to do exactly what the person above said, max their credit cards first. Cash advance if possible.