What people are proposing here is the same as if on September 19th 2014 the snp ad said we lost the referendum but are going to become independent anyway. Which, as well as being the complete opposite of democracy, would have lead to the fall of the snp government, possibly dissolution of the Scottish parliament, and probable violence on the streets.
What people are also proposing with another referendum is like yes wining in 2014, spending two years negotiating the terms of independence then having another referendum on that deal. Nonsensical, the UK government have a mandate and instruction from the public to leave the eu, nothing more, nothing less. To do anything else is flagrantly undemocratic.