The suggested implications that arise from leaving have been heavily based on the perceived damage to the economy. The basis for those implications has always been the volume of trade the UK does with the EU. Even if people aren't outright suggesting that trade will drop to zero, there's a reason that no indications are given to how much trade is likely to drop, and instead the volume of current trade is provided in its place.

This all comes back to media manipulation. Sometimes the media doesn't lie to you directly, they lie through omission. For example, take a look at this comedy sketch from The Guardian about the European Court of Human Rights:

https://www.youtube.com/watch?v=ptfmAY6M6aA

This video was brought out at the time when the EU referendum was being publicly discussed. It seems to make a good case for staying in the EU, right? However, there's one key bit of information that is omitted from the video, the European Convention on Human Rights which forms the legal underpinnings of the European Court of Human Rights was negotiated outside the EU through the Council of Europe:

https://en.wikipedia.org/wiki/European_Convention_on_Human_R...

https://en.wikipedia.org/wiki/Council_of_Europe

Do you see how, in the context when it was released, that the video could be misleading, even when there weren't any direct lies in the video (that I'm aware of)? I'd suggest it'd be easy to assume after watching the video that giving up the EU also means giving up the European Convention on Human Rights, even when that's not the case.