It could be some of both I guess. In my opinion the "h" word is overused as a quick and easy "gotcha" and it typically doesn't really provide much insight into the substantive issues.
My primary concern is that the use of dark money channels appears to make it easier for foreign entities to influence the elections in the U.S. It's not difficult to imagine a foreign entity sending a not so subtle message to an elected official "If you don't back arms sales to country X, you'll get hit with millions of $ worth of negative ads in the next election cycle." (or some other such influence)
I'll concede that I have not investigated the legal issues in detail, but the government should be able to regulate foreign money without running afoul of the First Amendment concerns underlying the Citizens United decision (i.e. I can't see how foreign entities have a First Amendment right to express political speech in U.S. elections).
What is the law in Canada with regards to campaign contributions, political ads, etc.?
The question of foreign interference isn't just a concern for the US. We have our own, as well.
foreigninterferencecommission.ca
I don't know all the rules surrounding party fundraising and election expenses. But, as far as I know, only individuals are permitted to contribute to political parties. Parties also receive public subsidies, based on previous election results. The idea being to minimize the influence of large organizations like unions and corporations. That said, some have tried to game the system by giving family members, friends and employees funds and having them make donations far in excess of the individual limit.
Federal political financing in Canada - Wikipedia
There's no perfect way to make party and campaign financing rules "fair", as fairness is in the eye of the beholder. I think the most important measure is transparency - who is donating how much to what party or candidate - with an eye to
cui bono.
PAC's are relatively recent creations in Canada and their influence is far more limited than you would experience in the US. While political financing and spending in Canada has been steadily increasing, it is a laughable pittance compared with the US, even in relative terms. I'm not saying one system is better than the other, just different. A major difference is that it seems everyone is in permanent campaign mode in the US, which has to be exhausting for participants and the general public alike. That hasn't been the pattern here. Generally, you don't see or hear much political advertising in Canada until "the writ is dropped", i.e. an election is called, although the current leader of the Conservative Party is departing from past practice and is putting out ads, making speeches and staging rallies almost continuously.