The goal of Stripe is to make things simple. I shouldn’t have to implement a webhook to discover that none of my invoices are actually being paid. I’d expect a notification email to be sent to the account until that is explicitly turned off.
It's always a risk to make assumptions, but I don't think this specific assumption was unreasonable.
Stripe needs to offer solutions 100x better than what we build, 10x as fast. That was the premise of the original product, now the “easy stuff” is glossed.