The disruption this causes is considerable, and massively outweigh the benefits. I'm not really sure what the benefits are actually!
Of course. If you're too ill to be at school for ten days as a pupil or teacher that's fine, but the vast majority would be back within a few days if they even needed to be off at all! We must be losing 10s if not 100s of 1,000s days of schools unnecessarily, whilst not really preventing much infection ultimately (virtually all children will be exposed to it some time this year)