My word, I have no idea how anyone achieves anything online independent of huge corporations. I'm working with the new version of a widely used ecomm platform. The underlying code is good (unlike anything running under WP), but so far I've offered a patch for their upgrade tool, identified a less than user-friendly issue with the upgrade process, and found a fairly serious bug, which I worked around with the most horrid kludge: manually adding stuff to the database. Then I patched a theme to fix something I found irksome.
So that's required: GitHub, PHP, PHPUnit, Bootstrap based SCSS with webpack, SQL, Smarty and a few other things.
I'm not exactly a "full stack" developer; I can rock the back end and know just enough to tweak things on the front end, but don't ask me to build something from scratch. Getting this thing going has tapped every single one of those skills.
But what if you're just someone with no development skills who is trying to get a small shop online? This leaves you out in the woods, and subject to paying Shopify (and similar megacorps) stupid money just to get a store that might never sell a damn thing going.