Why is Warner Bros. Discovery putting old movies on YouTube?

Since those are mostly old movies, my immediate thought was: "maybe it's a new creative way to create a new income stream for hard-to-sell-otherwise assets?". If a decent enough number of users watch them, it could bring some cash to the publisher, couldn't it?

That's my thinking too. In fact, I was in a mood to watch OG film noirs, but between 3 streaming services, the only movie available was Sunset Blvd. Also failed to find any of the 1950s sci-fi movies I went looking for.

Indeed, nostalgia is a great selling point