Spotify is a bit of an oddball in the podcast world in that they're an all-in-one closed platform with a player and a production arm. They can easily feed user behavior data back to their podcast producers and advertisers.
Most podcasts and players operate on RSS feeds though. While they can very well target things via IP addresses and user-agent (no getting around that), podcasters and their advertisers don't have the capability to read/write persistent tracking data on the client, at least as far as I know. An advertiser would be hard-pressed to see that I personally listen to Stuff You Should Know and This American Life, even if the advertiser had contracts with both. The medium really hobbles how much tracking can be done.
Most podcasts and players operate on RSS feeds though. While they can very well target things via IP addresses and user-agent (no getting around that), podcasters and their advertisers don't have the capability to read/write persistent tracking data on the client, at least as far as I know. An advertiser would be hard-pressed to see that I personally listen to Stuff You Should Know and This American Life, even if the advertiser had contracts with both. The medium really hobbles how much tracking can be done.