Nothing stops somebody from making a toxic gas or a propane bomb to begin with. If anything, it's easier to make a propane bomb or chlorine gas than it is to obtain a gun, since propane is much more loosely regulated and chlorine is readily accessible in large quantities due to it's use as a cleaning agent. Even with less strict gun laws, it's still much easier to make improvised explosives. You can literally buy a bunch of bullets, which require no identification or background checks, open them up for the gunpowder, and use the gunpowder to create pipe bombs using everyday materials.

Yet people don't. And for good reasons. First, the effort to create your own explosive or toxic gas is significantly higher than it is to walk into a store and buy a gun off a rack and a box of bullets to go with it. Second, you don't just have an explosive or toxic gas lying around for every day use, so it's less practical for impulsive attacks. Third, it's illegal to own explosives or weaponized toxic gases without the proper permit, the explosives license being heavily regulated by industry and the weaponized gas permit basically only issued to research facilities with the controlled material only allowed to be transported and stored under strictly regulated circumstances. You can at least bullshit owning a gun license if a random citizen spots you with a gun. Lastly, usage of explosives or toxic gas requires a lot more training to use without killing yourself. Guns are, relatively speaking, much easier to pick up and use compared to explosives or gas.


But more generally, as I've mentioned before, gun control isn't in place to prevent all crime. It's to prevent a specific type of crime. It's foolish to throw out a law as ineffective because it doesn't tackle a very large problem by itself.

If the fact that criminals can still hurt people regardless of what you ban can be taken as a legitimate argument, then there is no law in existence that can stand up to that same scrutiny. Why regulate automatic weapons if somebody can still buy a semi-automatic and shoot somebody? Why bother regulating explosives if you can just buy a knife and stab somebody? Why bother regulating armed drones if you can just walk up to somebody in the street and donkey punch them? All of those questions sound incredibly dense. It'd be like asking why a new drug that's designed to treat cancer doesn't treat herpes. It's why asking how gun control can stop acid attacks is a silly question. If you want to stop acid attacks, implement laws that target acid attacks.

The point of any law isn't to stop all crime, it's that through the law you make it harder or more punishing to commit a crime, thus reducing it's prevalence. There is no perfect solution to all crime, so asking for one as the starting point for any debate is just silly.