Not sure why you are downvoted but this rings true to me.
On-topic: Wind power brings in about 20% of Spain's electricity, and that one fluctuates a lot indeed. I hope they put out a detailed post-mortem, I'd be an enjoyable read.
Some even borrowed the essence of it, posted it elsewhere and still downvoted, ¯\_(ツ)_/¯.
(also we're a bit early for a proper postmortem, but that's an inevitable reality of social media, got to get the talking points in before the facts)
I agree as well. And I think the gp (or the ggp?) post noticed that there is a lack of "spinning mass" to do frequency damping would have agreed as well. They could be merely suggesting to add just spinning mass synchronizers. These could be independent units, doing just that or maybe even convert some old power plants: "just" decouple the turbine from the generator.
The solution in either case is the same. Put enough smarts in the inverter for it to have "synthetic inertia". If we didn't have the ability to do something like that in inverters, the solution would be something like flywheels to augment the chemical batteries.