Those things DL mentioned don't count as experience. Because if we apply that standard to the Liberals, they should acclaim Trudeau for permanent right now. He's impeccably bilingual, young, charismatic, dynastic and has 3 years in Parliament. But he's the first to admit that now is too early, same applies for Megan Leslie. In a leadership cycle or 2, Ashton can run. But not now.
The main criticism of Trudeau ultimately isn't that he's inexperienced. It's that he's a legacy. The public is naturally skeptical that he's qualified as a result; no one wants to vote for the incompetent beneficiary of nepotism. That he's only been in Parliament for a few years wouldn't bar him from running if he weren't a legacy, but of course he wouldn't even be considered if he weren't a legacy because he wouldn't have any political clout (and probably would never have made it to Parliament in the first place).
Niki Ashton is different in that she is not perceived as a legacy and is thus not subject to that same skepticism (although of course she is sort of a legacy, just a local legacy rather than being nationally famous for being someone's child).