Imagine the sales pitch...

Nostr CEO: Our DVM consumes user's nostr data and builds detailed shopping profiles for them for ad targeting!

Corpos: Great! So we can put ads in their feed?

Nostr CEO: well, no. They make their own feeds

Corpos: oh... So we can like send them targeted messages?

Nostr CEO: well... No. they can block you

The information is useless unless you also control content discovery