What restrictive practices do you mean?
One problem with the big mining and steel industries was that whole communities were served by mainly one workplace. Closing so many in one fell swoop left unemployment as the only option for most workers, and the destruction of local economies, including the businesses that relied on the custom of those workers. Any Government that cared about it's people at all would have done it differently, either by gradual closure or alternative employment creation or both. What these communities are left with now, which took several years to create, is mainly retail parks - people working in shops to make money to spend in other shops, and lower incomes overall.
This assumes that these closures were in fact necessary, although by now the coal industry would be much reduced anyway due to lower demand.
As for imported coal, quality was very often lower (this according to my father who worked in a coal fired power station) and increased the costs of some industries. The effect of not producing enough coal for the country's needs has been that imported coal has also become more expensive.
I do wonder what the overall effect of mine closures, importing coal, lower incomes and unemployment has had on the UK economy since 1984?
