The way 99.95% of customers would replace a macbook battery is to take it to the Apple Store and have them do it for a fixed charge while you wait. It's a great service. Apple will still replace the battery in your 2013 MacBook Air. By contrast there hasn't been a first-party battery pack for the T400 in many years.

These "fragility" arguments always, as in the case of the OP, ignore the actual experience of owning and using the thing. People will adopt an ancient smartphone because they are locked into the idea that removable battery and removable SD cards are morally superior, and then blindly ignore the fact that the battery life sucks, the only batteries available are random chinese junk, the backs are easy to break and lose, SD cards are unreliable and easy to lose, and so forth. There is a reason that the market overwhlemingly prefers phones and laptops with fixed storage and integrated battery packs.