Oh man, did you see that video where the guy tried to replace a pressure washer hose fitting and it shot off like a rocket? It put a dent in his shed door! Those things hold way more pressure than you'd guess. I always turn it off and pull the safety trigger to release the built-up pressure now, even for small fixes. That garage flood sounds like a nightmare to clean up.
Seriously doubt it's that big of a deal for a simple hose swap. People online make everything look way more dramatic than it really is. That pressure probably wasn't even that high. Sounds like user error more than some crazy dangerous event.