I have a 50A Autel and I've never set the charge current below 48A. Why would you want to unless your electric circuit couldn't handle it?
Mostly for that exact reason. Some homes cannot handle that kind of additional load on the panel. Some people like to lower the amperage to be gentler on the breaker, wiring, and receptacle. Some like to lower the amperage to be gentler on the local grid.
Let's say there are 10 houses powered by a transformer, and all of those houses have two EVs in the driveway. Each one, for the sake of argument, needs 20kW to recharge fully. If all 20 off those got plugged in at 6pm when all those people got home (you know, at exactly the same time), and they all have 48 amp EVSEs, that's 960 amp (230,400kW) being pulled through the transformer (in addition to the base load of all those houses). Alternatively, if each EVSE was pulling 16 amps (which would still charge everyone up by morning), that would be just 320 amps (76,800kW) being pulled through the transformer. Keep in mind that the poor transformer was installed before EVs were a thing, and they never anticipated that additional 230,400kW.
And finally, if you are generating your own power from solar or wind, you may want to turn down the current to stay within what you are producing at a given time, so that you're not pulling from the grid at all.