Actually it is built on the fact that the left isn’t seeking to ban all guns.
Here is a link to a bill proposed by 165 Democrats that would ban basically every semiautomatic pistol in the country:
H.R.5087 - 115th Congress (2017-2018): Assault Weapons Ban of 2018
Summary of H.R.5087 - 115th Congress (2017-2018): Assault Weapons Ban of 2018
Most guns sold would be banned by this bill. Further, when pinned down about the lack of efficacy behind banning “assault rifles,” which are responsible for only a tiny tiny fraction of gun deaths, the left always responds “well we have to start somewhere” or “that’s what we think we can ban right now given the climate.” I’m sorry you can’t see this, given that it’s everywhere.