This may be true, but decent metallurgy and not cranking the boost way up compensates for that. I had a 300ZX Turbo that I purposely kept at stock boost most of the time; I sold it at 280,000 miles and when last heard from it was still running around North Texas as a daily driver.
I've got essentially the same engine without turbo, and well over 200k miles. But, let's face it - the 3 liter Nissan wasn't your average engine.