He was speaking from experience.
To be clear I don’t think this kind of thing is likely, but once again Honda is one of the best engine manufacturers in the world. Their engine tolerances, aside from perhaps Toyota, are just amazing. Those are the folks who spec the oil viscosity. I don’t see much upside, and perhaps some chance of a downside, from not following what they say. But if you or others here know better, publish your CV and we can judge for ourselves. Otherwise the average person is well served to follow the manual, keep it full, and keep it clean, particularly if the engine has no issues.
Shame, I thought this forum would be more useful.
Enjoy your weekend.