[p_l]

AFAIK at least in case of Google, they used to closely guard that data, if only for business advantage.

As in, you could only benefit from it if you used Google product, you couldn't get brokerage/raw data.

No idea about Microsoft, but I don't know if they have their own ad arm like Google.

[tomoyoirl]

“We do not sell your personal information. It’s more of a rental.”

[p_l]

More like "You can pay us to use the personal information to get the ad to the groups you want. But we're not going to share the information, because it's our advantage over you"