OP made it sound like tabs in the title bar was a new innovation.

"The parent post is overly strongly worded, but I agree with the meat of it: tabs should not be in the title bar of the window. It's worse usability for a space savings that really isn't relevant because it's so small."

I was nodding to this.

But I'm also someone who cares about vertical screen real estate (enough to call it vertical screen real estate).

So I was in a hypocritical conundrum. Do I care about the title bar, or do not care about the title bar?

Check firefox. Wait wtf, my firefox has no title bar! Did I customize it myself, I don't remember removing it???