I think PSL's winning ticket is neither the Presidential campaign nor the educational content. Other parties do those and aren't nearly as large or popular.

I think what PSL does well theoretically and practically is address intersectional issues and decolonization, anti-racism, and so on, which are the order of the day. Most PSL people I see, and this may just be good propaganda, are non-White and this tells me that they are effectively reaching out to POC communities and comrades in ways others aren't. Let me drop some older, experiential knowledge.

DSA, ISO, even anarchist circles, etc. have always had a White leadership and racism problem. Some organizations, like ISO (Trot, I know), would even dismiss the importance of racial, decolonial questions as "identity politics" that they didn't get involved with. Many were and are class reductionists that only want to discuss the problems of the proletariat, which of course includes cishet White men as a default. This can feel not only dogmatic but incorrect to comrades or potential comrades who don't have the luxury of keeping an issue in the abstract because they live it daily.

Rewind the clock 15 years ago, and, I'm sorry to say, no one really gave a fuck about Black people or decolonial struggles generally. No one even really cared about using slurs or making racist jokes or comments. Precious few cared to even carry it as a real issue, even among Left spaces as BLM was starting. Obama was seen as having resolved racism in the country, not a joke nor hyperbole on my part. It rubbed White men the wrong way to be on the other side of history and critique, which created a lot of problems in groups. Presumably, this is why Left spaces and organizations were maintained as predominantly White. It was a self-filtering, most POC didn't want to stick around to deal with that bullshit, but there was also gatekeeping of people who were seen as problems for criticizing these issues and in particular criticizing certain leaders. You can still see this play out on Hexbear, by the way.

Now, everyone likes to say and think they're allies. Parties and people want to pretend like that didn't happen and they were always anti-racist, but that's easy to say and hard to prove when there are still POC who were there and have not forgotten what happened not that long ago. You can see the same thing happen with the Democratic Party who rejected BLM when Trayvon Martin was murdered, Obama himself dismissed it, but now that BLM grew into this toothless iteration like to act like they are its champions. That shit might work on White people who want to believe they were always good, but it won't work on POC with half a brain to remember. Another example, albeit different, is how DSA handled the question of Palestine—not 15 years ago but 15 months ago!!

It seems that PSL does not have a reductionist (read, "reactionary") line. It has welcomed a lot of people who didn't feel comfortable with that shit and, unsurprisingly, feel comfortable in spaces where they are accepted and anti-racism is put into practice in a radical way. I'm not entirely sure but it seems they were practicing this since the beginning and have good credit on this to make newer people coming in feel at ease. Further, younger people are growing up already understanding intersectional issues as important and necessary to address. They don't have the same baggage from previous times. When they interact with a group like PSL, it feels like PSL has a line which matches the thought of the youth, which is critical. When younger poeple encounter other groups, it feels like walking into an irrelevant but well-preserved museum. I'm cishet but I would assume (hopefully correctly) that PSL carries intersectional thinking to its logical conclusion with regard to LGBTQ issues as well, which resonates well with the youth and those communities too. PSL rests in good theory on that front and I, personally, have a lot of respect for them in this aspect. I think that theory leads them to good practice which has led to a lot of support from these communities which previously had to stick to 'identity'-based groups, for lack of a better term. This allows PSL to grow in ways other groups aren't or are doing slowly.

I'm not a member of PSL, by the way, and have other critiques of them but this is good.