My first quilts where all done with scraps from garments. We paid no attention to what the fiber content was... we just used what was available. Quilts were some of the original upcycling. I too used whatever thread was in the (at that time 5 for $1.00) , batting choice was so limited... and poly was the only thing available ...and yes they all survived some extreme use !
Would we have some artists if they all followed one set of rules?! Would have inovation if tradition was the only method?!
Sew what makes you happy!