Many Leftists (and even liberal nonprofits) focus more on coalition building than organizing new people into the movement. I think this is un-strategic (it doesn’t change the landscape by getting those who are already on board to be on board), but a lot of the time the impulse to build coalitions may come from that it seems easier – you have all these people who supposedly care about The Issue, you just need to get them in a room, or at an event/action, etc.
Coalition building is not easier. Coalition building is actually harder.
When you’re organizing new people into the movement, you’re talking with them about what oppresses them. Maybe someone doesn’t make enough money at work, and so works two jobs, and never sees her kids, and what she’s willing to fight for is to see her kids. You get that person angry about their situation, you build collective indignation by connecting her with other people who have a same end goal, and you use that collective indignation to move your group into action, for example, lobbying for a higher minimum wage. In this collective you’ve organized, you’re dealing with deeply felt feelings of personal anger.
With coalition building, you talk with people to figure out What they care about (maybe it’s gender equality) and Why (maybe their story includes that they grew up with an abusive dad). For the most part, you can’t change What people value or Why — especially not in a few conversations. All you can do is break things down for people and change the How of what they care about (maybe they should also be fighting for a higher minimum wage because women are paid 70 cents on the dollar compared to men). You’re dealing much more in the abstract, and agitating people against their self-identity/ego.
Moving someone into action based on deeply felt personal anger/oppression will almost always be easier than moving someone into action by getting them to be consistent with their values/identity.
(And anyway, you know your fellow organizers on the Left are already way, way overworked.)
In this same vein, abstract community organizing around large ideas will always be harder than solid issue-based campaigns.
So in summary, focusing on coalition building (as many Leftists and liberal nonprofits are wont to do) is not only un-strategic — it’s also way, way, way harder than organizing new people into the movement.