Disagree, it would prove the holder of the ID has all the right credentials to live and or work in the UK. Its not a visa, Here in the UAE I cannot do anything without producing my ID, its required for everything even getting a mobile phone...but it works
As a Brit I could easily live in the shadows of the south of France whereas the locals were always being asked for their ID cards ...
... when I worked on the doors, in Nice, I'd sometimes ask for a card despite being paid cash in hand
