faux leather is pleather, which is plastic. the process of mining, refining, and fabricating plastic causes enormous environmental damage at every step of the way. oil refineries regularly cause massive die offs of birds, small mammals, and EVERY local invertebrate. the degrading plastic from pleather garments (which break down after only a few years) produces microplastics and leads to groundwater contamination, killing off amphibians and, later, sea life. faux leather can't be repaired or recycled, only replaced by a new, equally toxic product.
tanneries are not exactly fountains of health, but a leather jacket uses the skin of a domestic cow that was already killed for meat. leather jackets can also be refurbished or recycled. once entirely discarded, leather will rot in place, rather than fragment into toxic forever particles.
leather is the product of an animal's death in a tangible, recognizable form that you can immediately assess. one jacket, one cow. you touch the skin of that dead animal and you flinch from it.
pleather can tell you that no animals were harmed, because it harms animals that you will never see. it outsources responsibility. you're not touching the skin of the birds that drowned in oil spills and the tadpoles that hatched into toxic rivers. the fish that will choke on the microplastics of your new jacket aren't born yet when you walk out of the shop. the material of the jacket is so abstract and your culpability is so obscure that you can believe what you are told: it is clean. you are clean. no harm, no foul.
but that's still not true.