This has been my experience with self-hosting too. There are so many different areas of concepts that need to form a cohesive whole. Following a how-to and pasting some commands can lead to something running, but then there are worlds of knowledge to actually understand it. Especially when complexity seems to increase exponentially.
Funny thing is that for every low-level concept I actually learn, the more I appreciate my OpenBSD computer that I mostly play around with otherwise.