Seems utterly pointless though...

With the proof of work approach, at least it's demanding the client consume some resources, though the 'right' amount is a tricky question, either it's so trivial as to hardly matter to the scrapers, or it's hard enough to put a dent in the scrapers' build, but human operated low end devices are royally screwed..

Here the crawler simply schedules a resumption and moves on to other work. The crawler doesn't need it right now and it's free for it to wait.