A definition is in order.
A Ratchet Buckle uses a spool and a lever to tighten the webbing. They have a ratchet wheel and a dog that locks the spool after each move of the lever.
A Cam Buckle uses a spring loaded cam, usually with teeth or ridges to pinch the webbing. Much lighter and simpler than a ratchet.
I have hung from high quality cam buckles (Northwest River Supplies and StrapWorks) with no problems. And I am a Certified Big Guy. Personally, I would not trust the cheapies one finds in big box stores or other such locations. I have cam buckle straps because I car-top canoes, and I want the best quality straps available. Saving a couple of bucks on a strap and losing a boat to the slipstream is false economy.
Same with hitting the ground due to a cheap strap.
My 2 cents.