I think in reality it will continue to happen that way. It seems to be a cultural UK thing that as soon as you give a shiny card (of any colour) to someone, they automatically become the most important person on the plane and it brings out the worst in people.
The staff are in a bit of a hard place really, they're damned if they do and damned if they don't. Either they enforce it rigorously and likely end up with a whole load of hassle for their trouble, or they take the path of least resistance and nothing changes.
I thought that golds and business+ cabins got to board at the same time.