5. It Can Exclude The Foreground
At times, the foreground may be unappealing, an element that may not add anything to the photo (and might even take away from it). A telephoto lens can look past the uninteresting foreground and focus on the interesting parts in the distance.
6. It Can Exclude The sky
Sometimes the sky in your shot will be uninteresting, providing nothing but empty space, or perhaps it may even be too bright, reducing the impact of the image. The telephoto lens allows you to cut out the sky when it is unneeded.