Interesting video on torch flashback and prevention

I've never understood, that if arresters are so important, why they are (were) not included. My first torch I acquired in the mid 70's was marketed by Forney and used re-labled Victor components. Sometime in the 80's I scored a new-unopened Victor kit. Neither had included arresters. I had bought them separate at some point. I had FORGOTTEN how important they could be re: these videos. I had forgotten the explosion could travel clear down the hoses / regulators and into a tank.