Another might be that you need to change the Dock setting for Prefer tabs when opening documents.
Yeah, well duh. That’s not how you support macOS tabs. You need to expose this behavior via the Window menu, so the user can select it when he wants it. Now you’re globally forcing the behavior for all applications. Perhaps that's what you want, but that's not the default and not preferable in most situations.
There also should be a Merge All Windows entry in the Windows menu. That other applications also haven’t got with the program yet is irrelevant, the menu entry should be added.
Also, the keybinding @wbond mentions in that thread doesn't work.
Also, this bug still exists that will leave ST in an unusable state if you close a tab the wrong way.
So, no, this behavior isn't supported. It's something all applications in macOS got for free, what @OdatNurd is describing probably also works in ST2. What's missing from ST3 is that it exposes the behavior properly and doesn't break when you use it.
I'm using the Adaptive theme because I got pretty tired of running into that bug by accident and having to restart ST. And it looks better