Yes, I know, prepared foods often have lots of sodium. Not sure what you mean about sodium into the blood stream from salt water. Sodium goes very fast directly into the blood stream. People that run out of sodium can go into a "fit" where the muscles all contract. Pouring highly salted water into the clamped shut mouth can make the body relax in seconds. But if you just drink salty water you are likely to barf. Having worked in a smelter in front of bottle furnaces for separating zinc from lead and then helped pour silver, I am familiar with salt loss. We often took 4-6 salt tablets per day and still the sweat would pouring off you would be absent any salt taste. At that point you knew to take more salt pills so you wouldn't have severe leg cramps.
I don't know about commercially now, but it was the standard at one time for certain uses and remains the standard for scientific work. Yes there are some chemicals that can only be removed by other measures as they will move over with the water, but still design makes a large difference. Distilled water from copper stills is often not acceptable for biologic work because the very minute traces of copper will interfere.