Not really no, it also likely isn't a surprise to the engineers and project managers working on these products. Which is likely exactly why they have standout battery life: the project managers knew AI wouldn't sell so they made the laptops appealing via conventional means anyway.
It's a common misconception but ARM isn't inherently better at battery life than x86 though. It's more that Qualcomm's designs are as compared to the companies on the market that produce x86 hardware.
TIL, I did some research because of your comment and indeed, the difference in their use cases is mostly a market thing, not so much a limitation of each one. This answer is particularly good at explaining that.
This article also does a really good in depth explanation about the topic although it does get a lot more technical but if you're interested, it's a really good read.
They absolutely would. They choose the chips included with the product, which screen to use, etc, and they can balance battery size with other considerations like weight. Battery life absolutely is a project manager choice.