Many folks do use it because it is extremely easy - add water only.
Another concern I have with Instant HPW is that the amount of protein is much higher than other glider diets - partially from the amount in the Powder being quite high, but also the mixing directions seems to make a very concentrated mixture. Gliders have been reported to have liver issues after years on diets that provide high protein amounts.
The Instant HPW and other add water only glider diets have only been in use for a little more than 2 years so there are NO observations of the health of gliders after long term use of these products. They may be just fine, or gliders may have health issues after being on these diets for several years, we just do not know. There are not many gliders that have been on this diet since it was first introduced, so most gliders have been on it less than 2 years.
I prefer to use a diet that includes only ingredients that have been widely used for many years with gliders.