Big engines last longer - truth or myth?!!

[B19GRR]

Due to the evils of the bargain barge thread ensnaring me with the mad urge to own a vast road going blimp for minimal outlay, it's got me wondering about the whole idea of larger displacement engines being good for many hundreds of thousands of miles. For example, there's an '88 750iL on fleabay, seller didn't put mileage in the add (why do they do that?!!) so I asked and got this reply:

"hi rob,there is no service history and mileage is around 180,000 low mileage for a V12. regards"

Now how can anyone really justify 180k being low miles for any engine, especially one with unknown history? As far as I'm concerned the pistons in a V12 will all have gone up and down just as many times as those in a weedy 1.0l 4 pot (assuming - rashly - the same gearing) to cover the same distance. The V12 has a longer crank - hopefully with a couple more bearings mind - so higher risk of flex, and it's got way more gubbins in the two heads than the 4 pot to wear out.

So can anyone think of any reason why a 4 pot shouldn't last just as long as a bigger engine?

BTW this is not a rant, please note conspicuous absence of angry smilies, none of the above blah is putting me off getting a big engine!!

Cheers,
Rob