Oh god not this nonsense again.
Most of the world is NOT in the EU.
If it were true that any country not in the EU must accept unlimited immigrants that would include all of them and I expect they'd be puzzled by the very idea.
"Mr Putin. We've just been informed by mumsnet that we're not allowed to limit immigration because we're not in the EU"
Additionally the 1951 Refugee Convention signed by 149 states spells out that it is illegal to enter a country without prior permission unless fleeing immediate danger.
Immediate as in the Gestapo are chasing you - which of course doesn't apply to someone leaving France.
Unlimited immigration is a choice made by governments when it suits their needs. You can support it or not.
But it's time to accept that Brexit is over. It's done. We are not Brexiting now and we didn't Brexit yesterday afternoon. We're not going to Brexit in the morning. It's not a process but a reference to something that happened many years ago.
(And no it didn't cause global warming either or the pole shift)
You don't have to like it, but it happened. By all means criticise what is happening now that you don't like.