Why steamships are limited in Empire: Total War

Are steamships worth using in Empire: Total War?

They have tactical advantages, but a good fleet of third rates can usually defeat them. The game treats them more like specialized frigates than an automatic replacement for the sailing battle line.

Steamships are useful in particular tactical circumstances in the game, but they are not automatically superior. Their model is essentially frigate-like, so a well-handled battle line of third rates can often beat them. Steam is therefore a specialized option within this ruleset rather than a universal upgrade. The exchange separates the game's balance choices from a simple story of steam immediately displacing sail.