WP users want a mature, easy to use framework, with lots of plugins, and a tutorial that can show you how to get anything done. Wordpress is the piece of software that kind of defines that genre. The fact that every host offers a Wordpress package seals the deal.
I maintain a few WP sites for small businesses. Precisely none of them would benefit from the kind of traffic spike that would incur a $50k cloud scaling bill.
If you’re running an online store, maybe, but by now almost all of those businesses are on Shopify where that isn’t an issue. 99% of all the businesses with WP installs I’ve touched would only be harmed by autoscaling instead of just choking on the traffic. Think local service businesses and restaurants.