I agree that there are some downsides, but regarding the conservative party leadership contests, it's probably fairly likely that the "who?" response would've happened under FPTP.
2017, likely that Bernier would've won, but I'm not convinced that he was more well-known than Scheer. Happy to be proven wrong here.
The 2020 result would likely have been the same as it is now. A small contingent of Sloan/Lewis supporters strategically voting would have tipped it to O'Toole.