All solved problems with well known solutions.

Networking is solved by processing commands in lock step (quake actually pioneered this).

Pathfinding has well known solutions like A*. That's really integrated with fog of war. In fact, it's easier to do today because computers are faster

Unit formation can be added but does not need to be. If you are doing high cps like in games like StarCraft, it's even preferable to the gameplay that you don't solve that problem.

And let's not forget the for these big studios, the solutions to these problems already exist in previous titles. They aren't starting from square one.

These problems are so well known that Indy game devs routinely solve them solo (see, games like factorio). Heck, the fact that you know to cite them speaks to how well known they are.

What's blocking new rtses by AAA companies is nothing technical, it's financial. Creating the assets, levels, and story are almost certainly a bigger blocker than any technical problem.