It’s easier and simpler to supply the country specific brick-to-wall cable (either IEC 60320 or IEC C13 to local) than it is to manufacture county specific power bricks.

Plus, as a user, it's great to be able to only change the cable when traveling to a different country, instead of having to haul around adapters and stack them.

It's only two or three conductors, at a lower current, and they're significantly larger. It doesn't seem too crazy that the AC cables hold up better.

I got a Razer once, and the power brick's integrated cable came with pre-frayed insulation, no extra charge. That laptop had tons of hardware bugs, too.