Scale is the mechanism that ties the two together. In a salt or mineral system, calcium hardness and drifting pH deposit scale on the chlorinator's plates. The cell then has to work harder to hit its rated output, and working harder is what shortens its life. By the time the owner notices — chlorine that will not hold, an error light, a cell that has to run at maximum — the damage has been accumulating for a year or more, and the invoice is for a cell rather than for a bottle of acid.
Salt pools also drift alkaline as a matter of course. That is not a fault; it is how the chemistry works. But it means pH has to be actively corrected on a schedule rather than watched, and stabiliser has to be held in a band that is high enough to carry chlorine through summer UV and low enough that the sanitiser still does its job. Get those two right and a cell lasts the years it is supposed to. Get them wrong and it does not.
The running-cost question is the other half. Pool equipment is often among the larger electrical loads in a Baringa home, and a single-speed pump left on a builder's default schedule is frequently running longer each day than the pool's actual turnover requires. Working out what that requirement is costs nothing and changes the bill without buying anything. Where a replacement genuinely is due, the numbers on a variable-speed pump and its payback period are worth seeing before deciding — including when the payback does not stack up.