Not true

It may have used some space that might have been useable for shops, but when it existed, I used it a few times ; go through to departures and at some point before heading to aeroplane, had to go to the US pre-clearance desk and get the immigration completed.

Could then continue shopping to your hearts content

On arrival in the US, the passengers were nicely bypassed around the immigration desks straight to the baggage reclaim and then , as normal, through customs