Why science fiction calls so many warships cruisers

Why do science-fiction games use so many different types of vessel called cruisers?

Because cruiser historically described a broad cruising role as much as a fixed size, making it a flexible label for the largest non-capital surface combatants in a fictional fleet.

Cruiser historically described a cruising role as well as a broad category below capital ships. That flexibility gives a fictional fleet room for vessels with different missions under the same general label. A designer can use cruiser for a large non-capital combatant without matching one precise historical type. The multiplayer game Dreadnought provides an example with its artillery cruiser terminology.