Yes and no. Sure, there is no point in building an e-commerce website for a small business, which is exactly who Shopify targets. It’s the equivalent of how WordPress pushed web developers out of the blog and basic website business.
But at some point the scale tips towards custom development and it’s important to understand how e-commerce websites are built (e.g. routing, caching, tokenisation, PCI, encryption). Financially shopify falls off too. I work for a $100 million revenue retailer so that 2.4% cut gets expensive.