This is a lie - background checks or not, it is still illegal for felons, etc to buy a gun.
The background check is one of the appropriate enforcement mechanisms against illegal gun ownership.
Your positiion is comparable to saying that even if the drinking age is 21, stores should have no right to check I.D. before someone buys alcohol.
Given the information I've seen that the majority of these nutcases shooting people up at random are
on some form, or have
been on some form, of psychotropic drugs intended to control mood or personality disorders, I would suggest that anyone diagnosed and prescribed a regimen of drugs for this range of disorders should be entered into some kind of database. This database should be included in the NCIS program. If their names show up on the database, they should not be permitted to legally acquire firearms, just like the criminals listed in the database.