I agree. Don't use hot steam.
I prefer to have a relatively clean engine without spending hours detailing my ordinary grocery-getter.
I've cleaned engine bays countless times using the typical high pressure wand found at those DIY, coin operated auto wash stations. First I spray the dirty parts with some sort of cleaner. I've used special engine cleaners (for really dirty jobs), ordinary household degrease (my normal choice), the special "engine" selection of the pressure washer, or the ordinary foamy detergent from the pressure wand. It helps to wait a few minutes for the cleaner to work.
Then I use the high pressure washer in the "wash" setting. Use some common sense here; i.e. hold the wand close to the filthy transmission case to blast off the caked on gunk but do not spray a lot of water inside the air intake or try to clean the inside of your fuse box while holding the nozzle one inch from sensitive electrical components. In other words, if you're drunk or really stupid, don't try this on your car because it is possible to cause damage if you're a total nut case. Otherwise, you'll be fine.
After you're finished with the soap, switch to rinse to get rid of the suds and you're good to go. I have used this procedure over many years on a wide variety of cars, including my old air cooled VW with a primitive and VERY weak ignition system. I have NEVER had a car fail to start after pressure washing the engine bay nor have I ever caused any damage.