Value proposition on Open Source Tech (like Zcash)

I do like Zcash and i do think their anonymity feature is stronger, better implemented than any other coin.

However, I struggle to understand what the intrinsic value of the Zcash network is if, as soon as they manage to improve the underling technology, they make it available to other networks to implement.

If Zk-SNARKs are implemented equally on all chains thanks to Zcash team improvements (and sharing), what would the coin gain from it? How would it manage to stand out, be unique and be used?