They were not ads though. The companies did not pay for those, from what I can tell. Microsoft seemed to really thought they were being helpful here.

That's a generous interpretation.

I see it as just preparation for selling the space. After a few months of "tips" they go to companies and say, "hey, you know those tips we have in our PRs? You can be in every 10th one of them for X dollars?"

I also get tons of helpful product recommendations and tips in my TV shows, every 20 minutes.

In media, we call that a House Ad.

Advertisement, noun. A notice or announcement in a public medium promoting a product, service, or event or publicizing a job vacancy.

There is no way they didn’t think they could sell those spots in the future.

First hit is always free

“Ad” doesn’t mean “paid for”. A “tip” linking to some other place, injected into a place with no permission or context, is an “ad” in every meaningful sense (and if this “tip” system were left in place it would soon enough be turned into a pay-for explicit ad system). If someone at Microsoft deludes themselves that they are just trying to be helpful, that doesn’t change the impact and result of their actions.