Well, I don't know that to be true. Engine longevity is so subjective and based on so many variables that it would be hard to give you a hard, fast number to hang your hat on.
As an example: if the engine is turbocharged, then it will make more horsepower and burn more fuel over it's life. The increased cylinder pressures associated with this simple, taken for granted these days, fact will increase wear rates and usually does result in shorter OH intervals. Almost all 92's were turbocharged while many, many, many 71's lived as naturally aspirated engines...apples to oranges.
Factor in oil change frequency, air filtration and full throttle operation and you can see that the equation is a moving target based on who is doing what and how in what latitude.
Your source is, most likely, referring to the 70's and early 80's version of the 92 that I already spoke of. That era gave that engine a poor reputation. Later versions and replacement part improvements changed all that.
I ran them in a fleet of 150 buses, for many years, with good reliability and "nominal" lifetime characteristics. Of course, they were subjected to a rigorous maintenance schedule during that time and, adherence to that, more than anything else, was supremely responsible for our success in my opinion. As they say on TV though, your results may vary.