Actually, it's an accepted practice in the Canadian brand of party politics. That's why we have official party whips. Look at the system on the federal level. Instead of representation by population, we have "ridings" gerrymandered to prevent the majority of the population from determining who runs the country. That means that regions with no population have much more of a political clout than they would in a truly representative system. Ok, that's what we chose as a nation, so you're MP is supposed to represent YOU and your little neck of the woods with 15,000 voting adults and has the same voting power as someone representing ten times as many people. However, a party whip negates all that. Instead of you voting for the best interest of your community, all of a sudden you have a party Comrade-whip telling you how you should vote on this issue or that issue, even if it's contrary to the interests of your community.
Realistically, having the office of the party whip is a great argument for switching to the rep by pop model. That way, the party with the greatest number of votes has the greatest number of seats and gets to determine how to run the country based on the will of the people.