Ummm...Yeah!

Look at it this way. The manufacturer decides what weight and spec oil is to be used in the engine they produced. Not me. I am not a petroleum engineer or a synthetic oil chemist. The manufacturer has to pony up for repairs if the engine grenades while taking the kids to school. They spec the oil accordingly. I am perfectly OK with that reasoning. Have been for more than 40 years and dozens of cars and motorcycles. NEVER have had an oil related engine issue.

That said, the problem occurs when someone thinks they are smarter than the engineering team that designed the engine and it's lubrication system. They try the latest and greatest oil supplement, or they cheap out and buy dino oil (can you even get that anymore?) Does dino oil meet the SN spec Toyota recommends? Or they go and get a $9.95 oil change at the corner lube shop, trusting that the shop will put in the correct spec and weight oil.

(We can sidebar on why my daughter driver a 4Runner now instead of her Equinox with the ruined engine) OIL SPECS MATTER...not the manufacturer so much.
Use the spec oil the manufacturer recommends in the range of weights they recommend and you will be just fine.