In addition to the other answers:
Does this mean that it is best not to use any salt at all?
Certainly not. Salt is necessary. If you don't eat enough salt you may end up with hyponatremia.
Hyponatremia is the most common electrolyte disorder. Its frequency is
higher in females, the elderly, and in patients who are hospitalized.
The incidence of hyponatremia depends largely on the patient
population. A hospital incidence of 15–20% is common, while only 3–5%
of patients who are hospitalized have a serum sodium level of less
than 130 mEq/L. Hyponatremia has been reported in up to 30% of elderly
patients in nursing homes and is also present in approximately 30% of
depressed patients on selective serotonin reuptake inhibitors.
Apart from them it is a condition which is quite common in people who are running a marathon and loose a lot of salt through sweating, while drinking too much water
See eg: http://www.nejm.org/doi/full/10.1056/nejmoa043901
This is also true for less intensive sports:
Sodium depletion is a recurrent theme in heat cramping, and is
reported to be one of the factors contributing to cause, treatment,
and prevention of exercise-associated muscle cramps .
Stone, M.B., J.E. Edwards, C.L. Stemmans, C.D. Ingersoll, R.M. Palmieri, and B.A.
Krause. Certified athletic trainersʼ perceptions of exercise-associated muscle cramps.
J. Sports Rehab. 12:333-342, 2003. cited in http://www.csun.edu/~lisagor/2009%20Fall/608-09Fall/608-1.Sweat%20and%20Sodium%20Losses%20in%20NCAA%20Football%20Players.pdf
In that paper you will also notice that some people lose a lot of salt through sweating, and for those people salt intake has to be higher.
Finally since this site is about skepticism: some groups are clearly vulnerable to hyponatremia. For those people it is perhaps a bad advice to limit salt intake. The major reason why salt is seen as 'bad' is the fact that it causes high blood pressure. But it only influences high blood pressure in a relatively small group of people.
Dietary sodium restriction for older hypertensive individuals
might be considered, but the evidence in the normotensive population
does not support current recommendations for universal dietary sodium
One segment of the public health community—funded by the the Na-
tional Heart Lung and Blood Institute and endorsed by many journals in
the field—has decided that salt is a public health menace. Therefore,
salt consumption must be drastically curtailed. The force with which
this conclusion is presented to the public is not in any reasonable
balance with the strength of the evidence.