@Purple Library Guy: I think that is in part a matter of style (in Civ we always had the warmongers and the builders, and Civ always excelled at the latter). But it is also a matter of difficulty level: on higher difficulties, first you need a very strong military early on just to survive (in fact, surviving the early wars and barbarians is one of the biggest challenges). Second, because AIs get so many bonuses taking stuff from it can be very valuable: steal a worker from city states before they get units, or try to get some well-developed AI cities, or to capture wonders instead of building them (in higher difficulties, early wonders can be basically traps if even possible to get first). Third, it is much less viable to beat the AI on some other things like founding a religion, so fewer options. (I think high-difficulty Civ is a much worse game...) But even then, to not fall behind you need to think a lot about when you can squeeze workers or settlers and buildings into the queue; people will debate a lot about whether to build two units or three before the first city or whatever the meta is.