The presence of the cat alone will deter rats from nesting nearby. The cat doesn't have to kill the rat just has to make it uncomfortable enough to leave. I work in fire protection in NYC (in the area referenced by the website and their experiment even) and see it all the time
This link speaks to a different point with regard to effectiveness, not apparent enjoyment. (And to be fair to the barn cats, they did pretty well keeping not only rats and mice down, but also snakes and scorpions)
They don’t hunt rats because the rats are large enough to threaten the cat. They probably would win 95% of those fights cleanly but it’s risky enough to not be worthwhile. Enjoyment is certainly not a differentiating thing.
These are urban rats specifically which are larger and may not apply to country rats
