The point GP was trying to make, if I understood it correctly, is that large policy changes have social costs you need to factor in even if you're going to do them anyway.
If a government doesn't keep that in mind it may bite them back somehow (see the beginning - as opposed to the follow-up - of the "gilets jaunes" movement in France).
" is that large policy changes have social costs "
The 'large policy changes' will have completely varying consequences across the economic spectrum, for good and bad, which is the general problem with centralized planning.
So if the government 'shut down all co2 emitting factories' it might have small consequences here, and terrible consequences over there.
But if the government institutes a 'carbon tax' that makes your 'pet toys' and 'medicine' 10% more expensive, then given the inelasticity in demand and surpluses derived from medicine, people will continue to buy it at the same rate, and possibly buy fewer 'pet toys'. If travel rose by 20%, then maybe we'd see less leisure, fewer business trips, but the 'important trips' would still happen.
If a government doesn't keep that in mind it may bite them back somehow (see the beginning - as opposed to the follow-up - of the "gilets jaunes" movement in France).