Like engine oil, the fluid in a torque converter gearbox will lose its lubricity over time and develop a build of debris that will increase wear and tear. Torque converter automatic gearboxes tend to have a much better reputation for reliably compared to the more sophisticated dual-clutch transmissions, but I would still advise replacing the fluid.

Dual-clutch gearboxes tend to require a transmission fluid change every four or five years, I would argue a torque converter would benefit from a fluid change every five or six years.