My presumption is the notion is that if people would read the correct things, their minds would be expanded in the correct direction and suddenly they too would see that advertising is wrong (or any other preferred moral position). But let's say you're right and the person's idea was that if people would just read enough they'd come to the correct conclusion. Either way, it is not correct. That's now how reading works. You can find someone with any moral perspective who is widely read. Being widely read unlikely implies any moral perspective besides as a proxy for affluence and education.
They're not asking for someone to read some particular books they like, but to go reading around and sampling the variety. Your criticism only really applies to the former.