Because I can literally walk away in the middle of a debugging session, grab any random notebook in the house, travel to Djibouti and resume exactly where I left off (ok, replace Djibouti with a random coffee shop). It has completely changed how I work and I love it (mosh + tmux = <3).

ADD: I do switch frequently between my desktop and multiple notebooks. Working this way means I can have a beefy/noisy development server and a light & quiet notebook which just needs mosh.