I happily hack every day on a project that is self contained in a single 12K line (and growing) file. For me, splitting into multiple files would have negative utility. Everything is essentially in one place. I can find anything I need for my project with '/' search very quickly in vim.

My style is obviously not for everyone but it works great for me. I programmed for decades with traditional file splits and only in the last few years have I switched to single file. I have little interest in going back. For me, it is liberating to stop thinking about directory layout entirely. It also helps me to use simpler tools (I only use vim with no plugins) in part because I don't need help managing multiple files.