The 'Project Fear' syndrome is their only argument.
No one is disputing that wiz. I never have.
But what I am advocating, and it is a complete and utter indisputable fact, is that if we leave without a deal and have to trade on WTO terms, we will take a hit. It is not up for debate, it is just plain and simply obvious that if our products become more expensive because of tariffs (and we're talking MUCH more expensive in some areas), we will do less business.
Add into the mix that standards will decline because we have less regulation (see USA example above), it's not going to be good at all. Plus the fact that countries will know we are desperate for a trade deal and will be able to take us for a ride.