I need to see what you have and really you need a plumber to do this right. I must say I have never had a flood from a washer and I have never turned the water off when the washer was not in use.

The electric ones work great (I had the type where the water was always off unless the washing machine was on, this meant the hoses were not under pressure for long periods of time).

Twenty years in the trade I’ve never seen catastrophic damage from a washing machine (though I know it happens). Poor workmanship in bathrooms and kitchens leads to most water issues in a home.

My set up is in the basement with its own single post shut off.

I ALWAYS turn off the water supply when done with laundry. It's a great habit to get into.

It would be great if you had easy access to the shut off valves for ease.

Congrats on the new house. I haven't run the plumbing yet for my laundry room or the stackable washer/dryer in my in-law suite, hidden in a closet. I plan on putting the water shut offs under the laundry and kitchen sinks instead of at the back of the washers. I want easy access to shut off the water but out of sight. Also, I put the washers on the basement/ground floor where the concrete floors are sloped to floor drains if there is a leak.

It'd probably take a plumber 15 minutes to do. Give a couple of local plumbers a call and asking for their minimum charge.

In a previous home (also 100yo) we had a stackable w/d in a closet that backed up to a bathroom. I had an access door into the closet installed in the bathroom, I could reach in and shut-off the valve. However, I'm not in the habit of shutting it down every time.

This water shutoff at the W/D "problem" would be better fixed by a psychologist than a plumber.