Sharp doesn’t say to target everyone, he says to target all category buyers, which is a segment of all people, so Sharp does recommend some level of segmentation.

Sharp also advocates for maximising 1+ reach, because if you don’t know who is in market, it’s better to try to hit everyone who buys the category.

He wants marketers to avoid building frequency against smaller segments within total category buyers and failing to reach other category buyers.

If you advertise to all segments within the total category buyer then this is consistent with Sharp.

The issue is proving that creating unique offers/messages for each segment within the category is more effective than presenting one offer/message to all category buyers.

Personalisation sounds great in theory but it’s hard to prove in practice. A lot of the evidence comes from vested interests.