People who think that automation is currently increasing unemployment don't generally just talk about jobs lost during the Great Recession. They see an overall trend of reduction in employment and wages since at least 2000.

You're absolutely right that the recession was caused by a financial shock. The thing is, a normal effect of recessions is for productivity to increase; businesses lay off workers and then try to figure out how to run their operation more efficiently with less workers, that happens in every recession. The difference might be that this time, it is easier then ever in the past for employers to figure out how to do more with less workers (because of the internet, and automation, and computers, ect), and so even when demand starts to come back up as the GDP grows again, they apparently still don't need to hire many workers.

The economists making the automation argument aren't saying that automation caused the great recession or the loss of jobs that happened then; they tend to think that it's a long ongoing trend that's been going for quite a while, that it was partly hidden for a few years by the housing bubble, but that the great recession has accelerated that trend by increasing the need for employers to find ways to be more cost-effective.

Edit: the main assumption EY is making in this article seems to be here:

Since it should take advanced general AI to automate away most or all humanly possible labor

and I don't think that's true. I think that a majority of labor done today, either physical or intellectual, is basically a series of routine or repeatable tasks, and I think that a big chunk of it could be done by either narrow AI software or robotics or internet-based logistics.

Anyway, you wouldn't really have to automate most or all of human labor to create an unemployment crises; if we hit long-term unemployment levels of 20%-30% that would probably not be sustainable without some fairly significant social and economic changes.