You're missing the point of standardization - it's not a legislative process that requires implementation, it's a documentation process to show what has already been implemented and how you can interoperate with it.
Webmention already has multiple libraries and services implementing it.
And in cases like this, standardization is just about the only way to ensure the feature's success. If every blog/publishing engine developed their own proprietary service for tracking linkbacks/mentions, it would likely never get off the ground at all.
