My only beef with shopify is that I don't see any of these fast growing etailers using them. I know why (makes no sense to give up that kind of % when you're at huge scale) and I wonder if it will hurt them in the long run. They seem to just help people with the MVP of their store.
Beyond a certain scale, (a) the benefits from controlling the software get bigger and (you don't have to do shipping, promotions, inventory, UI etc in a way that is supported by shopify) (b) the cost of doing your own software is less of a barrier.
Benefits like accessibility to non technical people don't mean anything once you hire specialists to be in charge of things. T
Off the shelf software that a non specialist can use makes sense for SMBs. That's shopify's target market.
We constantly have larger retailers replatform to Shopify who previously were spending 100k or more on their ecommerce software.
(I work at Shopify)