I don't know, just seems a way to try and jack up a coins value over its grade.
CAC offers a highly expert opinion at a very modest price. Please note, I used the word "opinion". CAC is not always consistent and often, others disagree with their opinions. Some of those who disagree are highly expert and many of those who disagree are highly non-expert.
Some coins are worth submitting to CAC and others aren't.
Some coins bring more money with CAC stickers - sometimes much more. Other coins barely benefit from CAC stickers.
Many coins are more liquid with CAC stickers, even if they don't bring noticeably more money.
Dealers can benefit from CAC, and so can collectors. And both groups can be hurt by it if they pay too much for CAC coins or their non CAC coins bring less than they would in a CAC-less world.
Edited to add: Thank you, Hack.