Okay, I'll be very brief on that.
First of all, there is a principle with insurance that if you don't have the issue of what's called “moral hazard”—where people will take undue risks, including deciding to take more unemployment—you would like to have full insurance, and you could make an argument for a no experience rating in that case, because all the unemployment is due to cyclical changes.
On the other hand, if the system of insurance encourages people to take more layoffs than they normally would—and of course businesses may actually participate in that as well.... For example, I know of teachers at private schools who only have a one-year contract and then go on unemployment insurance over the summer. That allows them basically to collect insurance, and that saves the private school from having to pay higher salaries as a result.
If you get those situations, you could argue for partial experience rating—not full experience rating, but partial—with the idea that those businesses that tend to have a higher layoff experience would end up paying more. So they would try to avoid some of the actions they take that lead to layoffs when it's not just a matter of cyclical effects.