Not very comparable since FPS games are much simpler mechanics wise, and I haven't played Halo. Regardless, in all these games they spend time teaching you how all the mechanics work. It's been a long time since I played FA singleplayer, but when I did I certainly didn't come out of the experience understanding what reclaim was, what stalling mass/e really does, what buildpower is, how the flux economy even works, and I didn't even know you could upgrade mexes. There's never even anytime where your opponent is playing with the same rules as you. They don't use reclaim and mexes to make their units, they just spawn out of nothing, so you never even properly interact with the mechanics of the game. Not understanding what;s going on is not core to the singleplayer experience, it hinders it. You have more fun when learning new things and understanding what's going on.
It is clear to me that you could create a campaign where you start out by learning how to collect mass, through mass extractors, and converting it into tanks. Shown that there's a simple ratio of factories to pgens or mexes to pgens. Once you are competent at that you get sent out to the field where you are instructed to secure the mass deposits before the enemy, so that you can produce more units and defeat them. You can introduce reclaim in a similar way. You can be instructed to raid their engineers before they build the mexes and get the reclaim. You can be instructed to drop areas with transports to get them faster. You can encounter an enemy that has a T2 factory and be instructed that once your opponent has T2 tech you should probably get it too.
You can do all of these things while still having a storyline, and still having scripted events and units spawning out of nowhere as well. It is how every decent game operates these days. You get a trickle of mechanics over time and instructions how to use them, mixed in with scripted events where using those mechanics is necessary, and mixed in with a storyline, and mixed in with scripted events and whatever. It's literally what game design is.