The issue isn't "banning all guns", it's banning all assault weapons. You definitely can ban every single semi-automatic AR by passing a law to do so. Rubio' point was that there is a specific assault weapon ban, which Nelson outright stated that he supports, number and all, that only bans 200-ish specific assault rifle models. The issue is that there are far, far, far more models of assault rifles than just 200, so that specific bill, the one that a lot of people are rightly clamoring to get passed, won't truly be effective simply because you can quite easily buy a functionally identical semi-automatic AR that is not one of those 200 models. On top of that, you have to take into account the thousands of models of bolt-action rifles, shotguns, and handguns.

The issue that Rubio was bringing up was that the discussion, for better or worse (probably worse) is far more complicated than a lot of people think. You can't just say "pass the assault weapon ban bill!" because there are still countless other assault weapons that wouldn't get banned under that bill.

So my point to yours is just to clear up Rubio's point since that final statement in the comment you're replying to was a little foggy. Rubio never said that you can't ban assault weapons and not ban all guns, he said that the drafted legislation we have now is not going to be effective unless that bill is extended to all assault weapons, and that's where you're going to run into a huge problem with damn near every single member of congress. That is, for them, too radical a law. You may have noticed in that discussion that Rubio directly asked the other two senators if they'd support expanding the bill to ban all assault weapons and they entirely avoided the question.

I'd say that we probably should ban all assault rifles since they serve basically no practical purpose aside from, admittedly, being quite fun to shoot. But, for nearly every single lawmaker in the country, that is too radical and therefore it is highly unlikely that it'll get passed any time soon. Because Congress is made up of a bunch of corrupt, spineless cowards who won't ever do a goddamned thing until it directly affects their paycheck. Sadly, that's our situation, and the only real solutions to our problems are more work than they can be bothered with. Golf is more important.