Of course the effects of salt are temporary... as the salt is eventually flushed from your system.
But salt causes the body to retain water...that raises your blood volume and that raises your blood pressure.
Blood Pressure : Why salt is bad
Now, if you are fit, it's okay for a short time.
But if you are obese and already have high blood pressure, that is a real concern as continuous high blood pressure can damage all kinds of parts of your body.
Plus, of course, they can lead to heart attacks or strokes.
And considering huge numbers of Americans are obese, eating less salt should be a top priority for them...it is a simple and easy way to reduce the damage to their bodies from high blood pressure and/or reduce their blood pressure.
Unfortunately, most foods people love are LOADED with sodium.