No, that's exactly what I'm talking about: They'll buy the md5-email-to-cookies from one provider (e.g. Lotame, Liveramp, etc) then use that to onboard email+c

No, that's exactly what I'm talking about: They'll buy the md5-email-to-cookies from one provider (e.g. Lotame, Liveramp, etc) then use that to onboard email+contact data they've purchased from companies that have email address-to-personal data (e.g. MVF, ZoomInfo, etc). IF that was done as purely a lead qualification step, it's a good way to take legitimate content syndication done by a third party into direct marketing, but there's no technical reason they need to be leads or have any level of qualification -- and only a weak market force (poor conversion rate) that prevents it from being more widespread.