Where it can be done with H5 and CSS3 we use those things, we don't invite complexity for the sake of it, but it's really very easy to run into the limitations of CSS3 when doing something even slightly unusual.
Vue replaces the dom of wherever the app is, so the choice is between having everything within a single app div or having a ton of apps talking to each other. Given that the ton of apps solution still breaks fairly essential functionality (for online shopping) and requires a fair amount more structure it's a bit hard to see the benefits.
A large majority of whizz bang the design team decides, can be done just with HTML 5 and CSS 3.