The warp core was originally a space babble replacement for a boiler on a steam ship, since it was based on WW2 navy ships. On old steam ships literally almost everything ran directly on auxiliary steam. As a result of probably not revisiting this since the 60s: everything in trek runs directly on warp core plasma.
WW2 Iowa class battleship had steam turbines
Yup almost 3000 liberty ships with triple expansions and heavy oil fired boilers were built during the war boss.