I think you rather missed the point there. Thatcher’s main aim was to destroy the communities - the coal mines closing was almost incidental.
There was an interesting series of documentaries on Thatcher last year. Ironically she had an admiration for the work ethic of the miners and the social cohesion of the mining communities. But that was trumped by two over-riding political motivations: a pragmatic decision to close uneconomic pits, regardless of the wider social implications, plus a more philosophical desire to destroy the power of the unions (especially the NUM) which she regarded as undemocratic and an existential threat to building the free market economy and smaller state she believed in.