You have a fundamental misunderstanding of both how a grid in blackout mode appears to a lonely inverter and what means of coordinating inverters that are available to said inverter.
Imagine you're trying to coordinate a choir of ten million singers that are scattered across a radius of a thousand kilometer, that all sing into their individual Ham radio. And you need it to come out in a perfect unison that sounds good for those who tune into the mixed broadcast.
"A problem of coordination" is perhaps correct, but it neglects the difficulties involved
Thing is, it's not ten million - it's several orders of magnitude fewer, particularly if we're starting with just a selected list of generators.
Also we know the locations of the generators, so we can calculate the phase shift and control them accordingly. At thousand kilometres it's around 60 degrees anyway, so not catastrophically huge.
But also, it isn't just generators, it is also the indeterminate loads. If you have nearby loads switching on and off that are similar sized to your local inverters, that is a complicated controls modelling problem.
I'm pretty sure in grid terms, 60 degrees out of sync is catastrophic. I'm pretty sure you'll be disconnected by protection circuits before it gets that far out.
Superluminal information transfer would be more useful for other areas than grid synchronization, but yeah we don't have crazy tech like that. And if we attempt to synch to a 50hz frequency over the internet means a 10ms latency difference results in 180 degree out of phase input.
And even if we did have the superluminal grid sync signal the propagation of electricity itself is slower than C and you'll need to consider perceived phase synchronization over distance.
Microwave, hell, even GPS-based time sources exist.
If I can sync ALL my [important] servers across the globe to the EXACT same time (under 2 microseconds variance in the last 7 days), and all that on the off-the-shelf hardware, surely a NATION can devise something better?
Imagine you're trying to coordinate a choir of ten million singers that are scattered across a radius of a thousand kilometer, that all sing into their individual Ham radio. And you need it to come out in a perfect unison that sounds good for those who tune into the mixed broadcast.
"A problem of coordination" is perhaps correct, but it neglects the difficulties involved