Canada

Hey buddy, we don't live in a PR country. Voting ABC means getting whoever can win in our local riding win. In my riding, over the last few elections the NDP has finished with abysmal numbers compared to LPC and CPC. A voter going NDP instead of LPC in this riding is a boost to the CPC candidate. Conversely in ridings where NDP has better chance of winning, a voter going LPC gives a boost to the CPC candidate. If all voters were informed ABC voters we'd have more LPC and NDP MPs and fewer CPC ones, likely resulting in more supply-and-confidence governments. I'll go a step further. If Jagmeet had his head out of his ass, he'd have began being strategic about this and explicitly run candidates only where he's got a reasonable chance to win and where he's got a chance to flip a lib, and not run candidates where he doesn't. The latter giving more seats to the CPC. If the LPC falls behind or is just as diminished as the NDP, I'd say the same thing about them. They should only run where they can win, and not run where the NDP has good chances to win against the CPC. We saw this play out in the recent French election where the NFP and Macron's party withdrew candidates in order to win more seats altogether than NR.

I think you might be confusing what ABC means. ABC doesn't mean vote LPC if you don't want CPC to win.