I don't quite understand what you're saying here - that after 24 hours, things will be defrosted and rotted enough that the fridge/freezer will stink forever? That it should be taped closed and the whole thing disposed of after the event? Or are you saying only if you open it, it'll never be useable again? I have experienced a number of multi-day power outages, and have never had to tape a fridge shut and not use it again, so I disagree pretty strongly with that advice.
Absolutely agree with preemptively emptying fridges/freezers and leaving doors propped open.
How hot was it when this happened? Were you there to manage the situation or did you have to leave?
If you have to leave in a hurry and are not able to empty your fridge, and it is hot, and you are not able to return for a few days, then yes, your fridge will probably never be usable again.
If your fridge is in a cool basement, then yea, you probably just have some food spoilage.
That's much more useful, nuanced advice than "if it's been more than 24 hours, tape it shut and throw it away".
My experiences have been in more moderate climate, probably temps in the 15-25 range. That said, it also depends what's in the fridge - I moved into an apartment where some beer had exploded in a left-behind beer fridge, the entire inside was coated in green mold for several months. Treatment with succession of soap, bleach, and oxiclean, and it's still in use to this day - so contents of the fridge matters too.
I think your timing is off here. I lost power for about three days during Hurricane Charley. This was the middle of summer in Orlando, Florida so hot hot hot. As far as I remember, my roommate and I left the fridge closed and evacuated. When we returned, the contents of the fridge were spoiled, but I don't remember anything particularly horrendous about it.
Like we are able to find preserved remains in ice of people who perished in these harsh climates, as opposed to a warmer climate where all the tissue would be putrid immediately.
Soooo many students were like "This fridge is a loss" and would just give them to me.
It's not worth it. You will never make the fridge use-able again.
If you have to leave ahead of a disaster, consider emptying your fridges/freezer and propping the doors open.
Obviously this advice is strongest in warm areas.