The indented kraft-paper (or similar products from U-line- corrugated packing wrap) are stiffer (paper towels get shoved aside by heavy-bodied snakes) while still being
absorbent & offering some traction (much better than smooth paper like newspaper). They come on large rolls that can be cut to fit the cage in one layer, unlike paper
towels. I've used these products in the past & found pro's & con's: it really depends what you're keeping, if the cost & pro's will benefit you. None of my current snakes
shove their substrate around so I use a layer of paper towels with about an inch of mixed Carefresh & clean paper shreds. None of these options are going to add to the
cage humidity either, so keep that in mind.
As far as the original question, I don't see why a blanket or towel cannot be used for substrate, EXCEPT that you NEVER want to feed a snake on them: it's way too easy
for them to catch their teeth on terry loops or most any fabrics, & then you're dealing with emergency surgery & their possible death if they ingest it. Blankets or towels
can be washed, disinfected & reused, to their credit. ("greener" option)
One more option you might not have thought of is the use of indoor/outdoor carpet, if you don't want to keep spending money on throw-away substrates & IF you don't
mind having to wash them. It comes in various colors, & some varying textures, it's all polyester so it's extremely durable (even bleachable with no color loss) & with
no backing (do NOT use regular home carpet) you can shake the rinse water out & use it damp (to add humidity until it dries) if you want. Large home improvement
stores sell it in rolls 12' or 6' wide....it's thick (great traction) & when I had a BCI, she did great with it. (snakes can still catch their teeth on it so always feed on some
sort of "plate", but it's stiffer so very unlikely to swallow the stuff) You can cut extras to fit cage for quick change, & leftover pieces can be rolled into snake-tunnels...
Example-
https://www.homedepot.com/p/TrafficM...144H/203240740
Cuts easily with good fabric sheers.