Salt intake is often considered one of the main factors behind high blood pressure. But the evidence supporting this idea is very weak, and eating less salt has a very marginal effect (and could sometimes even be dangerous).
Likely, there are other factors, like high levels of insulin, that play a much more powerful role in raising blood pressure. Professor Grant Schofield has written a very interesting piece on this, and even had a letter published in the Lancet:
High insulin causes salt retention, that can result in high blood pressure. If you suffer from this, it might be a good idea to switch to a low-carb diet, that lowers the insulin. That means that you're treating the cause, not just a symptom.
How to Normalize Your Blood Pressure