Not at all rubbish! Certainly they can run longer than 30,000 miles if ridden like a cruiser. However, the US Dept of Transportation keeps statistics on all types of motor vehicles' life expectancy based on OEM data and state motor vehicle registration records. OEM engineers design to meet specific life cycle goals for emissions, warrantee and profit. I suggest a little research.
I am not bashing any Triumph sport bike nor any other OEM. What I can say is that rpm, piston velocity and cylinder pressure directly affect longevity. Use it hard and you use it up faster! Smaller motors work harder to make the same power at the rear wheel. End of story.