Yes they can be used as far as I know, just not in the region they are stolen in/blocked in, if I am not mistaken.
There are global criminal syndicates that specialize in stealing these phones and exporting them to other regions to then resell or use for spare parts.
Here in South Africa we have had instances where a stolen iPhone is reactivated/resurfaces in a neighboring country or somewhere in Eastern Europe or the Middle East.
Iāve been very curious as to where my Xs Max that was stolen from me early last year has resurfaced, I wouldnāt be shocked if itās found in Dubai or something.