In the early years of time-sharing computer systems in the 1960s it was common for a single institutional mainframe to control many interactive terminals.
Furthermore, in many operating environments, scarce server resources such as CPU-seconds were often metered and charged against the account of the user running the program.
A common scenario in the early years of computing was an overload condition known as thrashing where the aggregate server performance becomes severely degraded, such as when two departments of a large company attempt to run a heavy report concurrently on the same mainframe.
Use of a deliberate server hog is known as a denial-of-service attack, a behaviour exhibited by many viruses, worms and trojan horses.
It is also possible for a petulant or vindictive computer user to manually overload a remote server by unleashing a crap flood.