Going by the official lore, and the fact that damaged Z variants (brainless, scorched, crawling) have at least a reasonable amount of tissue (particularly muscle) remaining - I’d say only serious structural damage prevents revivification. “Skeletons” are covered in a bony carapace, they’re not actually walking bones. Blob can repair soft tissue very easily, miraculously so. However, it doesn’t seem to be capable of reconstructing a body from scratch. So stripping flesh from bone (butchering) makes revivification impossible for obvious reasons.
With pulping, I’m guessing that you’re destroying enough joints and bones to make the body structurally unsound. Putting a skeleton back together seems to be well beyond the blob’s capabilities. I’m not sure it’s even capable of regrowing individual limbs. Flesh can be mended, modified, and mutated, but spontaneously generating body parts is beyond the blob, as far as I can tell.