I play just about all of those always online games solo. On the original Division I had to rando a guy in for the final boss with the dude in the helicopter. I beat Division II solo.
Same with Wildlands and Breakpoint. Even though I did use the bots in both of those games. I'd just use the syncrhonized bot shot to kill like seven dudes at a time. Was pretty easy.
Again, I know the appeal, but I hate immersion breaking. It is like talking during a movie, it just gets on my nerves.
MP to me has always been for the more arcadey type of multiplay games. Like COD or Battlefield. Or for the special game modes like Survival or Raids in the Division series.
Division II was definitely tailored more to solo than the original was though. I would say the opposite about the Ghost Recon games. First one you could solo pretty easy, but the second seemed to try and force the issue by not including the bots originally. Thankfully they were added on later.
I'm hoping the bots are at least competent enough to gun down some aliens, but usually on always online games, the enemies spawned are directly related to how many human players are in your party. If they take the lessons that everybody else uses, then a person should be able to handle the amount of enemies spawned by their lonesome.