Pre- and early Neanderthals seem to have continuously occupied only France, Spain, and Italy, although some appear to have moved out of this “core-area” to form temporary settlements eastward (without leaving Europe). Nonetheless, southwestern France has the highest density of sites for pre- and classic Neanderthals.
There are sites outside of Europe which means that it was not only sewing.
https://en.m.wikipedia.org/wiki/Neanderthal Demographics
From your article:
They were expelled elsewhere. If they were not they would have survived.
It is also possible that they didn’t need sewing but are extinct because sewing allowed us to finally also settle Europe.