It depends. I do plenty of billable hours augmenting software teams. I'm delivering user stories every week. There's simply too much communication overhead in preparing weekly estimates for the same client.
I don't share the perspective on hourly making someone a commodity. Fixed outcomes can also be commodities. Clients can and do shop around estimates for the best price. The race to the bottom exists whether you're billing by hour or by outcome. You avoid the race to the bottom by what you sell, not how you bill. Wordpress themes are mostly a race to the bottom, regardless of how you're billing.
I don't share the perspective on hourly making someone a commodity. Fixed outcomes can also be commodities. Clients can and do shop around estimates for the best price. The race to the bottom exists whether you're billing by hour or by outcome. You avoid the race to the bottom by what you sell, not how you bill. Wordpress themes are mostly a race to the bottom, regardless of how you're billing.