As with so much in the world of uneducated people the Do Not store on side issue has been blown way beyond proportion.
Acetylene did build itself a bad reputation coming from France to the US where people who couldn't read or understand instructions managed to blow many buildings apart with simple devices like household lighting systems. PresToLite found itself needing to build a small city a few miles from Indianapolis to get the canned Acetylene business up and running for vehicles. As the city went up, buses and other vehicles, even electric vehicles, plodded along in the dark using Ham kerosene lights if they could afford the best.
Oddly, when canned Acetylene arrived in buses, the cylinder was used oriented slightly above horizontal. PresToLite B cylinders into the 1940s were built with gauges in the bottom so the user could determine contents remaining, and discharge valves located near the side of the head rather than centered.
In 2019 the uneducated masses only working till they can find a fool to pay their student loans hides from Acetylene peeing down their leg in a closet wondering how long the battery will last on their device, and will 911 send a big truck to save them.