That seems to be the implication of this Wall Street Journal piece, in any case. This detail in particular:
In 2000, Rick Wagoner was named CEO. He took the reins intending to reinvent the company. In one of his first moves, he decided it was futile to keep Oldsmobile. It proved costly, as GM had to compensate dealers who lost Olds franchises. Analysts estimated the tab at $2 billion.
Thereafter, Wagoner seems to have done a 180, clinging to GM's brands rather then shuttering the non-viable ones. The rest of his tenure is filled with stories like this:
In February 2008, at a gathering of auto dealers in San Francisco, Mr. Wagoner said that any specific talk about killing brands was "not a thoughtful discussion."
The conclusion I draw is that it was pretty much impossible for GM to survive without some sort of externally imposed restructuring. Any time it costs you $2 billion--and probably a ton of political capital--to take a step that preserves or restores the competitiveness of your company, you're probably going to avoid it. Which is what appears to have happened in Wagoner's case.
Update: Okay, "180" probably overstates things, since Wagoner wanted to reinvigorate some of the old brands early on, too. But the lesson of the Oldsmobile episode wasn't lost on him, to say the least.