

upgrading powerlines won’t fix power fluctuations :
It can certainly help
that is due to imbalances between production and consumption,
Those imbalances are usually localised (and so are power cuts, usually). Having multiple paths for power to get from generation to load will increase stability.
no amount of upgraded to transmission capacity is likely to help.
Better connections between Spain and France is certain to help. But EDF don’t want cheap Iberian electricity flooding their export markets.
Why is some unproductive discourse a problem? Why is it so severe that a (hypothetical) thread lock is needed?