They haven’t thought this through. There is way more to oil than just pumping it and using it for energy. There are numerous by-products from the refining process that we need for modern living. One example is plastics. Oh use recycled plastics you say? This may be fine for cheap Dollarama products but many products require high purity. One specific example are cables used to carry electricity underground. The tiniest impurity in these can render a cable useless. Even worse if the defect is not found until after being installed for a few months with exposure to underground water. When that happens, there is the expense to dig it back up and replace it. This is just one example, maybe you know other oil uses that we can’t just turn off.
For those who don’t follow Canadian politics, The Leap Manifesto was passed this last weekend by the national NDP party. It advocates not building any new infrastructure for fossil fuels. Former leader Thomas Mulclair went on television to talk about “leaving oil in the ground”. Their national convention was in Alberta and created great divisive forces. For Americans, it would be like making a proposal for no more pipelines or oil tankers while in Texas.