No support s extending to the calves for stability. never rely on the ankles for stability when using some elevation device.
Carpenters, drywallers and painters and even some electricians use stilts but their stilts have leg braces much like the braces that Polio victims and people with severed Achilles tendons had to wear just to be able to walk.
These accordion scissors devices are a pair of broken ankles waiting to happen.
Note they were firmly anchored together and were still wobbly