Without the ideas and an appreciation of how things will work in practical terms, worked out in advance, the history of revolutions suggests they will only open the way for different people who will still be oppressive power seekers, think Robespierre or Stalin.
The quote in full is this 'There is enormous inertia—a tyranny of the status quo—in private and especially governmental arrangements. Only a crisis—actual or perceived—produces real change. When that crisis occurs, the actions that are taken depend on the ideas that are lying around. That, I believe, is our basic function: to develop alternatives to existing policies, to keep them alive and available until the politically impossible becomes politically inevitable.'
Milton Friedman, Capitalism and Freedom, 1982, Preface. https://en.wikiquote.org/wiki/Milton_Friedman
Unlike the right, the left doesn't seem to be very good at this.