Here's an example:
MW2: Sentry Gun is a 6 Kill Streak
- I would have to get 6 straight kills. That's it.
Black Ops 2: Lighting Strike is 650 points.
- I plant the bomb (200 points)
- Let the bomb explode (300 points)
- Throw a flashbang in the enemy spawn, and let my teammates get 2 kills. [25 (x2) for Flashbang assist]
- Get a kill. Depending on whether how close they are to the objective. (100 or 125 points)
I just showed how you can get a 650 point streak with 1 kill. (The game mode being Demolition)
MW3 and BO2 made the game more friendly to objective-based players than just the players that can get tons and tons of kills.