Where do you get this date from ? Please see:
https://flatpak.org/press/2016-06-21-flatpak-released/
Snaps were originally created in 2014, were used pre-installed in the first UbuntuCore deployments in commercial dell iot gateways in 2015, about a year before flatpak existed at all.
When we started snap development, we actually took a look at the xdg-apps project (which later became the basis for flatpak, but was back then a single-developer side project and did not have a lot traction in the community), but found it too limited for our use case (desktop only, tied to certain services you did not have on server, cloud and embedded devices, etc)
I’m not sure how this myth came up that snaps were a reaction to flatpak, they clearly were not, they were the evolution of technology we started with the ubuntu phone.
Flatpak was only announced by redhat during the week where canonical was holding a sprint to finish the initial snap desktop integration for the 16.04 release. At that time snaps were already used a lot in industrial, cloud, telco, robotics, you name it…
… do you think canonical should have thrown away several years of work, should have told commercial and enterprise users to stop using snaps and should have instead invested into a project that had already been ruled out for its technical limitations at the start?