Yellow Cards

I think yellow cards in soccer are actually quite pointless. If you get two yellow cards it equals a red, which will get you kicked out for a game or two, but one card gets you sent to the sideline for a second and then you can go right back in after another whistle. Is this meant as a fear tactic, as everyone waits and watches you, only you, as the ref pulls the card from his pocket, or is it just an attempt to pull you off the field to calm yourself? The card is used as a means of caution as it were, but the ref tends to talk to players during the game and give them warnings. So are the cards just used as the final straw of cautions? Either way I don't feel it is necessary. If they want a player off the field then they should tell the coach to pull them instead of halting the game just to flash a yellow piece of paper in front of their face. People don't respect it and some just try to get as many as they can. If a player actually did something bad give em' a red, if not just talk to them and if it didn't work, talk to the coach and get em' outta there