Any certification process that simply involved rote learning or which could be googled wouldn't be worth the paper it is written on. I'm certainly not advocating that.
> Just because Joe has a piece of paper saying that he knows X, Y, and Z doesn't mean that Joe isn't going to take shortcuts that end up costing the company thousands or millions of dollars (or human lives!).
Sure, certification doesn't do away with the need for QA and internal processes. It just ensures that anyone producing software that targets certain markets will have a basic understanding of which corners they are cutting. The government, for example, could mandate that they will prefer suppliers who have a certain percentage of certified developers. Playing an averages game, that at least means that somebody in the company is going to know when corners are being cut, rather than just having a group of people hacking along.
> Because Joe has this piece of paper, companies may be lulled into thinking that they don't need to test him as hard or give him as long a trial period before entrusting him with critical systems.
As I said before, the assurances provided by certification are not for the benefit of employers, they are for the benefit of users. If your hypothetical company actually did this, then they would be a very dumb company.