I think people who know how to code and code for their day job really underestimate how hard it is to build these things. Even the weekend projects. A ton of these "weekend" projects, took a weekend to build, plus years of learning and research into the best most efficient ways of building those kinds of apps.
Building a startup is completely different from your faang / unicorn software engineer dayjob. Where everything is perfectly and comfortable setup for you. There is a team dedicated to making sure your code is deployed every day. The test harnesses are already built. You have dedicated designers telling you exactly how everything should look. It's all easy.
This is like the twitter clone effect. It's a cliche at this point, the casual "I could build twitter in a weekend". Why aren't there a million reddit clones? Why aren't there a million instagram clones? Why aren't there a million notion / canva / figma clones?
If it were that easy to replicate these things they would be out there.