The UK already has fairly strict terms on offline advertising: you can’t advertise bonuses or play on the fact people can “win” etc etc. I’m pretty sure that this is aimed at offline advertising but would probably strictly also apply to advertising on 3rd party UK company websites (ie: banners on Amazon etc), and it would apply to anyone, operators, affiliates etc who advertise offline.
It’s a pretty sensible move and the first real step towards proper regulation IMO.