Kitteh burrito works great on kittehs that didn’t start getting nails clipped until they were adults. When we get a new kitten, we touch the paws constantly, and start clipping as soon as those little needles are big enough to safely cut.
I teach our cats how to maintain their own claws, by demonstrating with my fingernails on the things they are permitted to claw, occasionally dosing the things they are encouraged to claw with catnip, and going total nutso on them if they claw anything else. It’s actually easier than litter training an abandoned kitten or feral cat.
We never had one like @anon29631895’s so I have no idea if I could teach her to cope on her own! I doubt it, though, if a sandy cardboard scratcher doesn’t work. I think I would try to teach her on a cedar 4x4 though.
To avoid damage to humans, to help shed the sheaths as others have mentioned, and also to keep kittehs from sticking to couches and carpets and clothing like velcro - accidental snags are upsetting to kittehs, potentially hurtful, and definitely potentially damaging to textiles.