What is the advantage to you over a normal laptop?

Lighter weight, cheaper, smaller form factor, not having to worry about syncing storage or things like messages across apps. Also basically a spare power bank for the phone.

Does it not bother you that there are things you cannot do,

Not really, because I can always SSH to my home computer if I need to have a full linux environment. The case for this is very rare though, and half the time its because I don't want to spend the time compiling stuff from scratch on the phone.