When politicians say we need universal background checks everyone cheers because people do not want criminals or mentally ill persons to have firearms and we don't want to see others hurt either.
I don't think many people have thought much further than that though. Universal background checks would mean that a background check has to be done every time the ownership of a firearm is transferred.
The problem is what you have to do to enforce universal background checks. It would require universal firearm registration. How else could you enforce it?
You may ask "so what? why is that a problem?" The problem is that firearm registration is the first step in firearm confiscation. Once a tyrannical government can easily locate the guns then they can curtail your gun ownership and more easily oppress you!
It does not violate the second amendment for the government to regulate the type of firearms you can own, what would stop them from regulating how many you can own?
Lets say we have firearm registration and one of our future presidents decides that you don't need to own so many guns, that maybe a person only needs one gun.
You don't need to look hard to find examples of how disarmed citizens are subjugated. Venezuela is a good example.