Comment by nine_k

I suppose it's relatively easy to make a compact OS which has barebone hardware capabilities: VGA / VESA framebuffer graphics, SATA, 1-2 NICs, USB2, x64 only. Early versions of Unix were tiny by modern standards. NeXT's GUI worked well on hardware which would be considered a toy today. They all already contained the key features which MenuetOS has. I suppose it's the support of a large number of advanced features (many CPUs, various filesystems, virtual memory + page cache, advanced IP stack, a ton of drivers) that makes a modern Linux kernel large.