Plastic combs generate static, and static lifts the cuticle. Over years, that shows as frizz and breakage at the mid-length.
Why neem specifically
Neem wood is naturally antimicrobial, which matters because a comb touches a scalp repeatedly and is rarely washed. The wide teeth of a hand-cut comb also distribute sebum down the strand, which is what conditioning actually means.
Looking after it
Wipe it dry after use, and never soak it. Once a month, run a drop of the hair oil along the teeth to keep the wood from cracking in dry weather.