Has this not been true since forever? I remember in college creating clones of twitter.
I have been part of vendor discussions at my company where the question is "why don't we just build this in house?". The answer to that question is: we don't want to own this, and all the complications that come with owning it. Uptime? Cost? Responsibility? No thank you.
It's why I can technically make a nice table right now in my garage, but I'm going to buy one from a reputable seller instead.