Steam still connects you to custom servers, and Valve still allows you to download the server hosting software. The part that went offline- rather, moved to CS2, was the matchmaking client.

The workarounds to WC3 require you to leave Blizzard designed software to third party support. I don’t recall WC3 ever having matchmaking, but the server browser and hosted game list were taken completely.

So, not for lack of trying on Blizzard’s part.