The application of the 1 bag in the cabin policy is being enforced everywhere: reasons are straightforward.
Firstly, it is in the T &C's of travel. Secondly, it generates revenue, checked and excess baggage, and finally there isn't enough locker space on a full flight for people to take more than 1 bag.
Anyone who is carrying more than 1 bag when they present themselves at the gate will not be refused travel, however: they will be asked which bag they wish to leave behind.