Lots of people use only a laptop full time.
I think the main concern is make sure it has plenty of cooling room under the fan area, they can over heat.

The main difference is that with a tower - if you need to replace an internal part it's pretty simple, lots of room to work in those big boxes.

With a laptop it's a much tighter fit and maybe generic parts won't fit.
I think if the main board dies then it is sometimes toast.
But I've never taken mine apart and don't plan to until it does croak. LOL

But the manufacturers do rebuild & refurbish them, so it is possible.

But I've seen replacement parts online for laptops so I know it's do able.. keypads, screens , memory , hard drives etc..