Before reading their statements, I would have thought that either Microsoft or Valve themselves could have purchased SteamDB. Especially Valve, so that many of these early leaked data could be prevented if controlled correctly. I think better quotes that explain why this is done are:

As you all know, mods are often built around a particular version of a game, so when there’s an update for it, your game that was perfectly modded and working the day before now just…doesn’t. SteamDB already tracks an incredible amount of information about game builds, depots, manifests, files, and update history across Steam, including years of historical data. Being able to connect that information with modding tools and mod metadata opens up some really interesting possibilities for making modding more reliable.

Over time, we want to explore how a mod manager could better understand which version of the game you’re running, whether mods you’re installing were built for it, and whether an incoming game update is likely to cause issues. It could also make it possible for Collections and other mod lists to better specify the exact version of a game they were built for, rather than relying on someone finding that information buried in a description, comment, or forum post.

After these explanations, it makes perfect sense to me now. Also the next paragraphs, the way this is layed out, suggest change could come in the future once both services are merged or operate tightly together. Notice the wording "for now" and "currently". There is not promise it won't change:

What happens now? Well, for now, SteamDB carries on as normal whilst we work with xPaw on the transition and start putting the team and resources it needs into it. Everything currently available for free will remain free