Wait, so you can now set up a hard cap on your spending and they guarantee they won't charge you more? It would be exciting but I don't believe they actually allow that especially as their competition also refused to implement that, in spite of it being no #1 requested feature for many years.
Okay, my bad, I was looking at this page [1] which says that the "Cost Management" feature is available for Pay-as-you-go subscriptions, but [2] is pretty clear on the fact that Spending Limits aren't available for Pay-as-you-go subscriptions.
So, TL;DR: Azure still doesn't allow you to set spending limits on Pay-as-you-go subscriptions
I wanted to link the specific article mentioning that, but it seems like this works now :)