Hi,
That's indeed the case.
And you would be able to do the same with Joomla article aliases on Joomla article listing menu items.
However, I don't see why is it a problem ?
Since these links are not referenced anywhere, then people won't access them.
Also, we usually recommend to enter the URL you want to be referenced on search engine in the "canonical URL" field of the product. That way, even if the search engines end up accessing the product page from another URL, they will ignore the URL and only reference the canonical URL.