I know. Friends of ours practically burned their house down when their dryer caught fire. They lived in a motel for months while their house was rebuilt.
But if I never ran the dryer while out, the laundry might never get done. I do try to make sure that the lint thing is spotless and the whatchamacallit is clean and unobstructed.
I have acquaintances whose dishwasher leaked water all over their newly refinished wood floors (while they were out.) I guess if this happened to us, we would sleep through most of it, unless the dogs noticed and began barking.
I suppose we live a bit dangerously.
In my parents house, you really did not want to be in the shower when the dishwasher was running.
But, there were times when the person doing the dishes was doing them while someone was in the shower (or knew that they’d need to take a shower as soon as they were done with the dishes), and so the timer. Yes, that person could finish everything else (and wait for the showerers to finish) and then come back to the dishwasher and turn it on. But the “coming back” part didn’t always happen. The timer would take care of that problem.
That and peak water rates.
When you kitchen timer is counting down until your turkey is done cooking, the stove clock is timing the beans and the microwave clock is pacing the pasta, you need to use the dishwasher delay to make your world famous chocolate mousse.
You make the mousse in the dishwasher? Adjunct to that is - you need a timer to boil pasta?
As for not leaving home while major appliances are running - how about leaving small stuff running? Would I court disaster if I left the food processor on? 
Staying home isn’t a foolproof defense against appliance mishap anyway. Two days after we moved into our new apartment, we were doing laundry. At some point, something started beeping faintly. We search all around, looking to see if there’s a smoke detector in a closet or some other such thing that the leasing office didn’t show to us. No luck. As it turns out, the beeping was a smoke detector, but in the apartment under ours. The washing machine was stuck and water was pouring out of it and draining into our downstairs neighbor’s laundry room for the past half hour. Water’s pouring out of their ceiling and down the wall. Shorted out their circuit breaker panel and a smoke alarm. :eek: eek! :eek: All of this happened when we were home.
Water rates? What be these?
(Said the backyard gardener, who is very glad that the largest unfrozen repository of fresh water in the world can be seen from where he’s sitting now.)
We use ours when we’re doing laundry and dishes at the same time on weekends. Start one, then get the other ready and put it on a 1-hour delay. We don’t have enough hot water to run both simultaneously.
100th post!