I just burned down my Kali install and I fired up a completely new box. As I was putting my favorite tools back on the new box, I went to grab Empire and I saw the following: "This project is no longer supported". Not that I was a heavy Empire user but I've used it and that message piqued my curiosity. While searching, I found another headline: "PowerShell Empire Framework Is No Longer Maintained" on Bleeping Computer. Tl;dr -- it's old, hackers (good and bad) are using it, there's newer stuff, and the developer(s) no longer feel the need to maintain it.
On the newer stuff front, we have Sliver which according to the description, and from my personal interaction, is currently in alpha. I will warn you right now, I trashed a Windows VM because something got stuck, I Ctrl-C'd out of Sliver and the Windows box got bricked. After the reboot, I login to Windows, still a brick. It was either elevate, migrate, or impersonate. Honestly, I don't recall and I didn't want to go through the hassle of recreating it to find out. You've been warned.