That is something that never occured to me. I recently played civilization, and I just realised that the way the mechanics works is almost the same as an RTS. The main difference is that you have all the time to make your decisions
Here are some example of similarities:
Buildings and unit have a production time, it will take X turn to arrive into play.
Movement has a notion of timing, be able to more a settler to a destination before another player.
Technological research and civic takes time to accomplish.
So time is omnipresent in those game, timing is sometimes crutial as completing something a few turns later will you make you lose some opportunities.
The entire game itself is a race to be the first / best civ in the world, so the notion of hurry and competition is there like in RTS.
Maybe this is why I struggle so much with civilization.
We are far from turn based board games, where when you build something, it's done immediately (most of the time). In puerto rico, when I chose to make a building, I pay the price and it's done.
I understand that board games are more limited in time and space, and they must deal with those constraints.
As for civ 5, they could have used a time frame like a board game, especially considering the civ the video game is based on advanced civ the board game. Instead they chose to expand and delay the time frame.
This is something I see often in strategy video game, things takes more time to execute requiring even more play time from the user. Making games long and unfinishable.
There is nothing wrong in using a short or long time frame, it just create a different experience.
But my recent realisation is that games labeled turn based happens to be behaving like an RTS due to the long time frame.
There are games like Xcom, that has timed events (reseach and construction tim), but they dont have a slow progression like civ (you just skip to the next event). I think what helps is that they separated combat from base management. This helps in making games less overwhelming. I makes less things to think at once. I generally prefer that model for video games, but that's another topic.