Valve doesn't but the companies that use Steam as a platform do.

For example, your Titanfall purchase on Steam is now useless, and actually it was useless for the entire time it was available for sale (since the servers were never operational at any time during the period it was available).

All of these titles they're talking about Ubi are available on Steam too (and the article specifically notes that some of them are still on sale with no indication they will be removed in less than two months).

"Steam games can't be taken away" is false, and "valve as a company hasn't taken away your orange box yet" is not a particularly interesting or insightful observation. And to be clear, they are legally allowed to do so under the ToS under some circumstances!

They don't, because unlike Ubisoft, they're mostly a middleman. They run the marketplace for other game vendors and so they have reputation to uphold. However, Ubisoft is primarily a game developer, so there is a moral hazard of them screwing you.

We all hate middlemen but this shows why they're needed (in the absence of regulation).

This isn't entirely true. Most (all?) of the games require the Steam client which they are constantly updating and increasing the system requirements for. Systems that could previously run the Steam client and games just fine can no longer run those same games after a while. If I remember correctly the Steam client no longer supports systems running Windows XP, Windows Vista, OS X versions before 10.10, etc... to name a few. This is currently preventing me from running some games I've purchased and I will no longer be making any purchases on Steam until they resolve this problem.

But they may change them. For example by taking out music or replacing with remastered assets. Disc based media cannot be changed after the fact.

What if Steam where ever to shut down? (E.g. it loses to Epic in the long run, or services like Game Pass consume the entire industry and render it obsolete)?

Not so far, but the day might come when steam closes shop and then good luck getting your games to work

Yeah, this is my take. I didn't trust Ubi before this debacle and I'm not surprised now. Now, if Valve, Epic, or GOG pulled something like this, I might be inclined to sweat.