I don't understand what people mean when they say "barely portable" about a device that weighs less than 10 pounds. You can't use a big laptop one handed in midair, but that's not "portability". And it can't be a weight hauling problem when small children can handle that much. What is the issue?
There's a difference between carrying ten pounds small distances for short durations, and carrying an extra two pounds over twenty hours of travel, across multiple connecting international flights in a single day. It's also not just an extra two pounds, it's an additional proprietary power cord, bulk, more mass moving in and out under an airliner seat, it all adds up. Especially when you're sleep deprived and physically exhausted.
Any amount of weight is annoying after that long, but if the extra laptop weight is reduced to 10% of your 25 pound bag then it's even less able to be the deciding factor between "portable" and "barely portable".