I understand this, But may I be so bold as to say it would benefit to keep work dry? The suggestion was so that distributors don't have to maintain their own stuff, and rather, port welcome more expediently since there has been quite a bit of work to apply much polish for something so beneficial.
Think MATE menu for a moment; a few of us who had been using Ubuntu way before GNOME Shell, CInnamon, Unity and the MATE project who checked out Linux Mint were infatuated with the Mint Menu, which was the precursor and root software MATE menu is based on. Even better; we could install and use it in all varieties of Ubuntu using GTK no problem, at least until some time ago.
Thankfully the project was forked and this software is able to be used in Ubuntu MATE, which presumably means anything Mint team does with it trickles down to us using Ubuntu MATE. But rather than having duplicate work and multiple varieties of Welcome self-encapsulated, why not give distributors under the Ubuntu brand the opportunity to build, iterate and produce a core which allows for less back-end and front-end work for everybody who publishes a variety of Ubuntu?
Personally, I've encountered nothing like it. It's the best first-time and subsequent user experience I've seen, with my limited knowledge. And I feel like it would benefit more than just our distribution if y'all feel like sharing. But if there isn't any interest in this, that's alright too; it was just an idea.