[Ballas]

It is to mimic the spinning turbine generators, which themselves act as flywheels, but in this case without the turbine part. The rotational inertia gives stability in that the frequency cannot suddenly change. I thought that was quite clear from the article?

[catalogia]

The article isn't unclear, it's just weird. Smoothing out the input power is doubtlessly the most common purpose of a flywheel, second to power storage, and both of those is what this flywheel is for too. Describing a flywheel in terms of a turbine due to turbines acting as flywheels is the part that's weird.

[happytoexplain]

As somebody without the domain knowledge, I thought the article did a great job of making it clear what the flywheel is doing (though of course it could be misleading in some way and I wouldn't know). I'm honestly a little confused as to the nature of your objection about which object is described in the context of the other.

[catalogia]

I'm not 'objecting' to anything and I don't think it's misleading. I just think it's weird to describe a simple machine in terms of a more complex machine by pointing out that in one aspect the more complex machine is doing what the simpler machine does.

It's like describing a light-switch in terms of relays. Not wrong, not even misleading, but normally you'd expect the comparison to be made the other way around; describing relays in terms of light-switches or the rotational inertia of turbines in terms of flywheels.

[Ballas]

I guess it is referred to in that way to give the reader context as to why it is needed now.