Can you improve arm strength?

QBs are criticized for their lack of arm strength

He can't make this throw, or that throw

His deep passes float on him or lack zip

Is that something that can be greatly improved in the gym/practice or just slightly, or not at all?

If there is a lineman who just needs to get stronger, no one seems terribly worried about it, just work out and get stronger

But I've never heard arm strength talked about like that before