The oil fired steam propulsion was standard for larger warships of the era. In the 30's engineers started to install internal combustion diesels to large ships.

The oil fired steam propulsion was standard for larger warships of the era. In the 30's engineers started to install internal combustion diesels to large ships. But the oil fired steam still persists. (When power/weight is more important than fuel consumption, but internal combustion turbine is too expensive.) This hints that it was designed to be large. And steam propulsion was selected because large enough diesels were not available.