You need to clarify your question.
You say they ran the oil I said and it blew up.
Then you said they used xyz oil and not the oil I recommended.
I’ll say this. It’s rare to see a catastrophic engine failure due to oil. It’s rare, but it happens.
One big mistake is using a true synthetic oil with alcohol. That’s usually a bad combination.
What you do see is power loss, less ring seal so less blow by, less time on valve springs (that’s a HUGE one) and generally a shorter TBO or time between overhaul.
And the false notion that cheaper oil is better because it’s changed more often.
All engines and by that I mean ALL ENGINES run on used oil. All of them.
Let’s just say that we ignore the output of the pump because it’s rpm and clearance related. But let’s use a wild number. Let’s say that the oil is in a “used” condition after 100 miles.
That is clearly longer than it takes to make 5 quarts of oil get through the system more than 50 times.
Being generous, we can say that after 100 miles both oils are now considered used. If you change your oil every 3k miles you’ve just run 2,900 miles on used oil.
A quality synthetic will be the better oil out of the bottle, after 100 miles and certainly after 8,000 miles.
So oil change regimes are a silly way of fooling yourself into thinking a cheap assed, outdated oil is good because it’s changed more often.
The lies we tell ourselves are far more ridiculous than the lies other people tell us.
In other words, a cheap oil is a cheap oil no matter how often you change it.