Some reasons I can think of, some of which may or may not apply to your specific examples:
Monetization: limiting the amount of actions in an addictive free to play game, and then offering to unlock more actions by paying money is a common way to monetize games.
Game balance: by limiting the amount of actions a player can make in a day, you can force players to think more about their strategies, instead of simply giving advantage to players who endlessly grind on your game. Think of this as the extrapolation of the "1 move per player" rule of most board games.
Regulations: some countries, like South Korea, have regulations that online game providers have to follow. I think some games have to limit the amount of time players can be connected per day.
You have to be careful though, because if your game is not fun enough, or if players begin to feel helpless, the fact that you can only do so much in a determined period of time could lead to your ruin.