You probably spend most of your time listening to popular podcasts with a large enough listenership that they can get advertisers. There are thousands of smaller podcasters that can’t get advertisers.

Also, most podcast ads are for direct response ads where the effectiveness of the ad campaigns can be tracked somewhat via coupon codes and that either are for large purchases (Casper, Warby Parker) or for subscriptions where the lifetime value of the customer and churn rate can be estimated.

You don’t hear that many brand advertisements on podcasts. That’s the market Spotify wants to go after.

Besides, an advertiser doesn’t need fine grained targeting to know that for instance anyone listening to “The Talk Show” or “Accidental Tech Podcast” is a probably a computer geek with lots of disposable income.