It's not ineffective in all situations. A single soldier, isolated from his group, fighting 10 seniors or children simultaneously, is not going to do well. Plenty of people are killed in the Middle-East from rock throwing.
It's not an implausible hypothesis that an invasion of Japan would have been a larger, and proportionally bloodier, version of the takings of Iwo Jima and Okinawa, two very bloody battles.
https://www.atomicheritage.org/history/japanese-mass-suicide...