Do you need to understand the internals of every tool you use? Do you know how the PHP interpreter works, the kernel, etc?
> Moreover I cannot install gem (and probably not Jekyll) on my shared hosting. Huh...
Why would you install a development tool on the server? Do you install gcc on servers too? That makes no sense at all.
> You can install it on a shared hosting, only requirement: Apache + PHP.
This pretty much reinforces my point: it does not generate static pages, and actually generates them on request-time.
> My answer is no: you can do something simple with a "hack it yourself" philosophy. And less of 100 lines of code.
Indeed, you can do that. You can also hack your own. gp's question was how this compared to Jekyll, and that's what I answered.