Many people I know use a laptop for almost anything, anywhere. When they arrive at the office, they hook it up to an external monitor, and use an external keyboard and mouse or trackpad. I prefer to have a proper workstation, with powerful CPU and GPU, lots of RAM and multiple large monitors. As it's rather difficult to take this setup with me to meetings, or when travelling, I still require a secondary device that I can take with me everywhere I go. Some people seem to be OK with a tablet for that purpose, but that just doesn't work for me.