ELI5: How does halting a stock market help during a large, one day decline?

I read that many stock markets have built in halts, if it goes down 7% then there is a 15 minute trading halt, and if it goes down 20% then it is halted for the day. Wouldn't markets continue to slide upon re-opening?

Submitted January 04, 2016 at 12:51PM by batman_catman http://ift.tt/1PbEvTh