Who ever had a warranty claim outside the standard Apple warranty (1 year) knows how difficult or impossible it is to prove that the reason for the guarantee already existed when goods are handed over, ie after purchasing! Important: 6 months of purchase, the burden of proof, ie the buyer must prove that the damage was already present at purchase applies!
My conclusion: If expensive equipment such as a MacBook I like to buy me the APP, mainly because of the 3-year warranty. And if you researched a bit on Amazon you get the APP also much cheaper than Apple (currently 249 EUR).
Important: The APP must be purchased and activated within the warranty year.