Steam has had voice chat (group and 1-on-1) for a much longer period of time than that. I've used it on a regular basis for the last 5 years or so, well before the current updates they've made.

What they added was voice chat to static groups[0], whereas before you had to invite everyone to a custom group chat every time. Definitely a QoL improvement, but not exactly "new".

0: https://steamcommunity.com/search/groups

The new chat is a huge improvement over the old one in terms of UX, but lack of persistent history is pretty pathetic considering the amount of resources Valve has available compared to a startup like Discord.

Steam has had voice chat for a while. This article is actually wrong, it wasn't added in the redesign.