If I'm in the market for a product, if a company makes a decent product chances are I'll find out about it by reading reviews, etc. I don't need ads for that.
Ads exist to make me spend money that I wouldn't otherwise spend.
Ads exist to make me spend money that I wouldn't otherwise spend.
So the ads are intended to help you avoid post-purchase guilt. Hence their emotional appeal: you're a certain kind of person etc. That keeps you buying MBs on a scale of decades, rather than jump ship to a lower prestige, lower cost brand.
The larger point is there are many reasons to run ads, not just to attract leads.
Reviews aren't enough for discover-ability, but they are awesome once you know the product exists.
I'm not convinced paid ads are the right move for me, but I do think general advertising (having someone talk about a product or service on a site that isn't yours) is absolutely essential.
Brand recognition has impact.
You might still go read reviews of the product first, but they still need you to seek it out to do that. That's where advertising comes in.