Why do reviewers complain about vibration and arm fatigue?

Solid-steel hammers transmit more shock than titanium or anti-vibration designs. Several high-trust community posters say basic steel hammers cause joint stress during all-day use, and one switched away from a competitor back to a shock-reduction-grip model to stop arm pain. For occasional use this rarely matters; for daily pounding it is the main reason buyers move to titanium or premium grips.