Home warranties can go in many directions e.g. in a brand newly built residence a warranty is usually good for the warranty of the products or particular item like a roof or boiler system. A warranty is usually "a year" in appliances and usually longer e.g. up to 20 years for items like a roof. Now when a warranty for a house that is older built e.g. more than 10 years old might not have any warranty on any items of the residence and would have "as is" in the contract and it's reasoning is that the item has lived it useful life. So a refrigerator that is about 10 years old is not going to live any longer and would have to eventually be replaced. So the builder or seller is not going to warranty that item. I have seen some items listed as warranty for life of the residence but would have to be back up by paperwork and some separate type of contract to the company of that item, e.g. "the roof".
I had this problem myself, when I purchase a residence in a cooperative that was in a newly built building but sat empty for 2 years. I requested a warranty repair on my stove and the company stated because it is 2 years old the stove was not covered under warranty, even though I just moved in and the item was never used until after the closing date. Unless it is completely covered by the builder/seller and/or it is written in the contract it will never be warranty by anyone but you paying for the repair yourself.
Now I have seen "home warranty companies" out on the internet, but is it worth it. It depends on a lot of factors of the residence that you're purchasing. It can go in many directions like I mention before. You can save your money for that rainy day or invest in a warranty company that you may never use or like you mention loop holes that it isn't worth it at all.
I would prefer to save my money into a bank account for that day when I need to replace or repair the item in the residence.
I hope I answer your question.