Earlier quoted context omitted.
> Comments often show the reviewers never read the paper. This. I was not in computer science, but in a different technical field, and this is sadly common. We would often have to appeal to the editor with "The topic the reviewer said we didn't address? It's in Section X. Get us another reviewer."
The biggest mystery in the whole thing is why someone who is volunteering to review papers anonymously would bother to do it badly when they could simply not do it at all.
* You do get academic points for chairing a conference, and as a chair, you do need to find reviewers.
* A colleague is running a conference, and asks you to do a favor. You want to help your colleague. Reviewing papers wins you points with them, and declining to review burns bridges. When you're running a conference, you'd like them to reciprocate. Plus, they might be on a grant / hiring / etc. board / committee / etc. later on. Burning bridges in academia is very bad.
On the other hand, there is no incentive to invest more than 30-600 seconds per review. Neither you nor your friend really have any reason to care about the quality of the conference.
As this process repeats, people put in less and less time each time around, since it doesn't matter. The process converges to random noise.