This is crazy. Just because the service tech told you something doesn't make it true.
I have an HE washer/dryer that predates yours. I got it them 10 years ago and they're still going strong. It was the Maytag Neptune, which was the first HE washer on the US market. There was a flaw in the door latch on the first year or two model but I was lucky to avoid that, mine is from just after that.
The washer works fine, although it is nice if you leave the door open for a day once in a while to dry it out in there otherwise, since the door is sealed, any moisture left in the drum after a cycle just sits there until next time you use it. It doesn't have anything to do with hot water, hot water only stays hot for a short time and hot water doesn't kill mildew anyway, if it did you wouldn't need to scrub or bleach the grout in your shower! Later models from Samsung and LG don't have this problem.
The dryer doesn't even have cycle times. It just runs until the clothes are dry. It does this using a dryness sensor, the same type which has been around since 1980 or so. If you do run it on a timed cycle, you can adjust the time it runs in one minute increments. So I have no idea what your tech was telling you about mandating short cycle times or burners that aren't hot enough.