@MichaelIgnotus here firaxcoms / chimera squad have solutions for the player: you must choose between missions using a game mechanic that removes the other options. For a major audience, this type of forced choice works best… whatever PP does to get the concept to players, a lot of them still won’t get it (specially first-timers) or will want to try and tackle everything nonetheless just because the game allows. I guess the ‘auto-defend’ would be a good compromise, however player forces would’ve to become more vast and expendable. This would change the game a lot.
So, I still don’t see a good choice here. This whole situation translates into another one of the “should PP be a niche game or an all-audiences game?” type. Firaxcoms went the all-audiences way and was very successful for that. PP went for a middle ground but that is much harder to achieve.
Even if the game timed missions in a way that made it impossible for any player in any situation do more than one at the same time, players would be pissed about it because it would feel forced since the base mechanics are based on freedom. It’s best to just present two or more options and force the player to make a choice, like we have with the synedrion alliance or firaxcoms.
That however cannot be applied to PP because it would change the game too much and it’s too late for that, but it could be taken into account for PP2 (which I hope will exist). I myself prefer the freedom of PP, but if the game is to reach major audiences, I don’t think freedom + explanation is the way to go. For now, in PP, I agree with you that this should be told repeatedly somehow, and if PP had more canon characters it would be easier.
Edit: just after responding this I read your suggestion for the wiki in another topic 
See, it’s a great thing as you described since it leaves much more of the strategy in the player’s hands. But you tried to explain it and took 2 big paragraphs with it. It almost seems as more text than the entirety of the tips PP gives to players. And that would need to be repeated. It’s difficult to do it in-game, and I wish we had “Central” to pass this kind of help to the players.