It WAS that way:
A Linux-based system is a modular Unix-like operating system. It derives much of its basic design from principles established in Unix during the 1970s and 1980s. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are either integrated directly with the kernel or added as modules loaded while the system is running.
Other people in this thread have already point out that the direction systemd is headed will leave us with 2 binaries: The kernel and systemd. What next, systemd incorporates a mysql server?