I looked for the recipe this comment was made in, and in the comments, the original author of the recipe mentions replacing whole or part of the oil with applesauce which might explain why.
The other place had something like r' I didn't have any eggs' that was all people giving 1 star reviews to recipes where they substituted Triceratops horn for chicken breast, and it didn't work well.
You can replace SOME of the oil with applesauce. But replacing all of it (which I did find on some really shitty websites) will not work correctly.
Fat soluble flavors will be diluted by the excess water as well as not giving flour anything to bond to. Less flavor, rock hard baked good.
If you want to try using applesauce, use unsweetened applesauce and only replace (at max) 50% of the oil required for the recipe. Results may vary, I don’t see the use in lowering the fat content of a delicious baked good. I’m eating that shit full flavor, full fat, full sugar. Just eat less of it.
Outside of that tangent, the gall of this person to say “I followed the recipe exactly” when their very first sentence contradicts that completely.
This isn't as crazy as it seems. In some bread and cake recipes, you can easily replace some of the oil with applesauce and have a successful bake. I've done this with muffins and banana bread to great success.
They're still being foolish as you need some fat for most bakes to work and using apple sauce introduces more fiber, protein and water instead of fat, but it's not a totally baseless substitution.
Baking is a science, not an art. You want cooking for that. You can't just randomly switch shit and expect it to work. If you must substitute, do some research first and expect to have to fiddle with stuff to get things to come out tolerable.
Apple Sauce is a mixture of pulp and water, what little fatty acids are available are tied up, so it does not function as an oil substitute. Oil and Water have completely different properties.
In the defence of this person, some recipes for desserts offer applesauce as a replacement for oil as a healthier option, like the mug cake I made literally 20 mins ago. This might be one of those