[Nursie]

>> Does anyone know if there is a reason elliptic curves weren't been mandated

Support still patchy ?

I work in this area (certificates mostly) and find issues every so often with various platforms having gaps in their EC stuff. That said most things can now deal with the base subset and sticking to (say) P-256 would probably be pretty trouble-free. Getting europe-wide agreement on this would likely be hard though, and european standards[0] often have stuff in that's not widely supported, like FRP256v1, which doesn't seem to be in openssl yet, or wasn't last time I looked, let alone more obscure or outdated implementations.

[0] - e.g. https://www.etsi.org/deliver/etsi_ts/119300_119399/119312/01...