It's already implemented. Not just a reference implementation, but production implementations by three (3) independent companies: ACINQ, Blockstream, and Lightning Labs. Tested on testnet that each implementation works with two others. They are now testing it on the mainnet. How impatient people can be? Should they put it in production without proper testing? Some of them are opensource, but support is not free. You realize they are rushing to put it to market, because whoever is first will get the bigger share of the profits from every institution who will be using it. But at the same time, they can not afford the screw up, so it's a balance between enough testing and hurrying to offer it to entities on the market. Be asured they will not take a single day longer then it is absolutely necessary.