There's a difference between saying "it's possible to exist without EU - see countries X and Y as an example" and "if we leave EU we will turn immediately into country X or Y". The first is reasonable argument, the second is completely ridiculous.
no-one ever said this
they were used as examples of countries that are successful despite being outside the EU
not that the UK would "be in the same position" if it left, i.e. becoming 10x richer per capita or starting to mass produce cuckoo clocks
Completely ignoring the fact that both countries are 100% aligned with EU on basically all laws and regulations, have open borders with the EU etc. etc. etc.
"Singapore on the Thames"
But I'd assume it's more remainers pointing out that GB wouldn't be like Norway or Switzerland being dismissed as "Project Fear" and rembering the double negative as a positve affirmation by the brexit shysters.