Google Voice still supports texting from their web page, but the feature to text directly from Gmail was discontinued a few years ago. It was a convenient feature, but now you have to use the Google Voice app or web page for texting.

I use it as my primary interface. I can't believe they haven't killed it.

I like it, it's useful, I rely on it, and it's from Google. How does it still exist?

no, it still exists.