I'm sorry but what you are saying is just flat out not true. First of all, can you explain how there is no guarantee you will be accepted as a PR? Are you saying you are half expecting your application to be rejected for spurious reasons? That's not how this process works. If you're eligible then you'll get PR, else that's not the fault of anyone but yourself.
Secondly, immigration to another country, any country, takes a lot of time and money, and often there's not a clean break between working in the home country and moving and getting a job in the new country. There's a huge amount of risk involved before you've even got the visa, and you're acting as if outland applicants have nothing to lose, which is not only wrong, but frankly insulting.
Thirdly, you say you cannot see why someone wouldn't be working while waiting for a visa, except I just listed several very reasonable instances of that right of the top of my head in my previous post, and I don't really feel like repeating them.