A 50%-good solution that people actually have solves more problems and survives longer than a 99% solution that nobody has because it’s in your lab where you’re endlessly polishing the damn thing. Shipping is a feature. A really important feature. Your product must have it.
(http://www.joelonsoftware.com/items/2009/09/23.html)
This article doesn't go into details about the history of why Etsy's architecture is the way it is. It's entirely possible that this architecture enabled them to launch and iterate faster at a critical point in their history, without which they'd be nowhere.
Do what you need to now that will work. If your project is successful enough to experience a few orders of magnitude growth it'll need rearchitecting in some way anyway; build the heavy engineering when you know what you need, not think you know what might be the pain point.