Firefox does that too and avoid this issue reserving a small space on right site of title bar. Not the end of the world.

Thanks for this reply. This comment chain sent me through an existential crisis.

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???