As mentioned, they work great as a "Touch Point" to maintain balance, but they are not safe to depend on to prevent falls or, as was discussed earlier, as a grab handle to use to pull oneself into an entry door with. And, on some surfaces, the suction cup grab handle can slide.
Something unsafe is really not better than nothing when it imbues a false sense of security. Especially when there is a better & safer way, and your health, safety and even life may depend on it doing its job.
I have two grab handles at the entrance to my Hunter, one above the other, and both are securely attached with 2 1/2" screws into both the metal door frame and the wood substructure. Took all of 15 minutes to install them.
But again, they have been discontinued and I guess it doesn't bother Home Depot to sell off remaining stock.
BTW: Has anyone noticed that safety is a sensitive topic for Moi ???