Another way to view this is that the main cost to the OC would be running the dryers. If 5 of 8 are using dryers then only three have opted out of using the laundry communal facility. If those three have preferred the convenience of drying in their own unit, then that is their choice at their expense but the communal facility remains available to them, just as it always was, even if they choose to not use it.
Yet another way to view things: If the OC originally provided either washing machines or a place to house and operate one’s personal washing machine, but did not provide electric dryers but did provide sun- and wind-powered dryers (clotheslines), then it could be argued more forcefully that the electric dryers should be either removed or put on five kWh counters since electric dryers were not part of the the OC communal facility.