Given that I have regularly put over 20000 hrs on my Mazda OHC industrial engines, I'd argue otherwise. I've got about 20 still in service that way. Two units with over 40K.

Sure, we get timing belts break, but those are easy fixes on the non-interference engine.

Only head issues I get are the occasional head gasket failure, and tar build-up on the valves. You can also run them out of oil and seize that cam.

That being said, the 16V head configuration on the new engine definitely has me a little concerned. Plus a balance shaft. No word on whether or not they are interference engines, but they show 4000 hr timing belt change interval.