Imposing a direct tax on a factor of production such as capital is a way of taxing the very process of production and wealth creation instead of taxing individual income or consumption. This involves substantial costs in terms of economic efficiency, and it harms the competitiveness of Canada and Quebec.
The economic costs of the capital tax are so obvious that the federal government has promised to eliminate it and the Quebec government has promised to lower it substantially. What remains is for the federal government to maintain this course and for the Quebec government to get back on track.
Links of interest
Appendix (in French only): Les coûts économiques de la taxe sur le capital