And if you had an eGPU?

Then you're stuck at your desk anyway, so you might as well use a desktop machine and take advantage of the additional performance and cost savings.

Being able to use the same device travelling and at your desk is really useful. Even if it were a case of only opening the actual editor at your desk and just working on emails/design docs/what-have-you while travelling, it makes for a much nicer workflow than switching devices.