The article you link to explains that the Three Day Week led to the collapse of the Conservative gov in 74, and while Thatcher became leader, she did not come into power until 79. If the power outages led to anything, it was to a Labour gov.

(this is unrelated to the correct statement that there were widespread outages throughout the 70s)

Those "disruptions" occured because of political action.

The disruptions in Texas are because their power grid and associated infrastructure is shite.

Entirely different things.