A simple answer is: yes, many people leave products in pouches in their kitchen closet. A complicated answer is: not everyone does that. And even those who do, they leave only particular objects in their kitchen closets.

Pouches come in several shapes and sizes. Some of them are simple plastic pouches. It may not be a good idea to keep a simple plastic pouch in a closet as it often lacks in valves, zip-locks, and other kinds of locks which can stop the inside material from spilling. Therefore even people who keep pouches in kitchen closets remain careful not to put these simple pouches there.

There is a second category of packages. They come equipped with elaborate packaging methods which make them an inexpensive replacement to glass and plastic jars and other traditional packaging methods. Stand up bags with gussets are an example of them. They can stand upright like jars, but occupy less space. Spouted pouches can also be left in the closet as their spouts are an effective barrier against spilling.

To conclude, yes there are some people who leave products in pouches in their kitchen closets but they don't leave just any kind of pouch there. They store only those pouches in the kitchen which are able to keep the product safe.