If I’m going to cook a roast, which isn’t very often, I do it on one of the weekend days. I would not leave the house and leave the stove on. And I don’t even like to use the Crock-Pot overnight, not because I’m worried about any potential issues, but because I like to stir whatever it is once an hour or so so that it doesn’t stick on the sides.
I will let an oven warm up, unattended.
Even that, is not something I do often.
Unless you leave it on as hot as it can get, for a bit, it shouldn’t be a problem. But. Food, especially a hunk of meat can pop, sizzle and spread grease.
There are several very dangerous variables that are too risky for me.
I’m paranoid (or cautious, depending on how you look at it) and would never.
My mom used to put things in the crock pot, on “low” and go to work, and it was fine. I am a bit too paranoid (or cautious) to do that. I am trying to remember if she would leave the oven on if we weren’t home. I don’t think she would.
People today are probably more apt to leave a crock pot cooking all day than the oven. We are all aware of the cost of heating an oven vs slow cooker. I, myself, do not leave anything cooking while I am away from home. The worry is me having an accident and not making it back home in the time frame that would be normal.