"The industry" has done no such thing, just Apple. Everyone else there is still mostly a standardised place at the top of the window which is the place where relevant information about the identity of the app you're using is conveyed.
However it's not like that on the iPad, and Apple has decided that laptops are just iPads with keyboards.
My apologies for not being clearer. Also, thanks for the counterpoint since it pushed me into a slight investigation to back up and refine my claim (always a good thing). I was wrong to say the industry has moved away from title bars. I should have said that there is strong evidence that the industry is moving away from title bars.
One thing, I guess there's a difference between a "title bar" and a "title area". The old fashioned title bar was colored differently than the stuff just below it. It was reserved for window controls and the title of the current document. I see that BBEdit still has such a bar. A title area (no one calls it that) is just a title bar without coloring so that it just blends into the area just below it. People just call that thing a title bar.
Consider this page from the Gnome project,
Header bars. The project strongly advocates combining the title bar with the menu bar and tool bar (the "strongly" part I gleaned from their forums).
Consider this page,
Add or Remove Title Bar in Firefox. The default in Firefox is to display no title bar. Happily, you can choose to display it; there's a setting in the customizations.
Consider this forum post,
Title bar?. The OP is bemoaning the loss of the title bar. Another poster on that thread claims "I don't see Opera or any major browser getting back a title bar anytime soon."
Now, what I see on Mac:
I don't have a title bar in Chrome. I've read posts on how to get the title bar back when running it on Linux, but the setting they mention is not available on Mac.
Rattling off a few others: 1Password (a program dear to my heart) has no title bar. Microsoft Teams has no title bar. OmniFocus has no title bar.
I think sometimes programs don't bother with a title bar if they're not document centric. That is, if there's no document having a title, then it foregoes the title bar. PCalc is an exception; it has a title bar without a title. Catalina's Mail treats the selected mailbox as the document and shows its name in the title bar.
I do understand the desire to save space. Heck, this thread is filled with complaints about Apples exorbitant waste of space in Big Sur. But, I think a small, consistently placed drag area is warranted. Consider Catalina's Dictionary versus Big Sur's Dictionary. The vertical space at the top is the same, but only Catalina's Dictionary has a drag area. This was not just an artistic decision by Apple, it was a removal of functionality and will be a constant source of friction.