You are taking a narrow view of the possible problems, which include adversarial strategies from outsourcing firms. It's not a matter of can things go correctly -- of course they can -- it's a matter of can unscrupulous actors exploit the chaos to bilk their clients. Historically that has been the failure mode, and the fracture points I listed were their tools of trade.
"Just use a platform / reputation firm / ..."
Yeah, we had those in the last wave of outsourcing, too. They were not able to tackle the "fraud-lite" problem for the simple reason that it was much more profitable to become part of the problem and ride the bubble until it collapsed.
time zone --> plenty of people will work during nights and sleep during days if they can 10x their income
cultural --> doesn't matter too much for software engineering. But I will agree that this is important for jobs like marketing.
legal --> a lot of companies have popped up to make it easy to hire around the world and stay compliant.