The "need" or not to do something is and
always should be left up to the decision of the person in control of their car, etc ... and that pretty much also goes with everything in life.
The discussions here are focused mainly on the science and controlled testing, and technically showing why thinner oil leads to more wear, etc ... not based on who should make the decisions for who about using anything related to taking care of a vehicle - nobody has ever said you "
need" to run abc or xyz ... apparently some people read way between the lines IMO. People can read the technical information, the controlled and even the "anecdotal tests", etc and decided what they think is right and make a decision for themselves from there ... like "Should I run 0W-5 in my engine to get more HP and MPG".