That's one of the very obvious misrepresentations thrown around by the Remain camp. The whole purpose of a points based system is to be able to increase and decrease immigration as required. It's not fixed. You ask for more points when you want less immigration, and vice versa. Honestly it's not hard. If Remain keep getting this wrong it is deliberate.
It probably is deliberate - just one to add to the many, many other deliberate "errors" promulgated by both sides. If you're watching the debate, don't expect facts! And if there are any, they will probably be dismissed as being the voice of "experts".