I just finished reading a book by one of the bleeding-heart libertarians. They view freedom as primarily a means to achieving altruistic ends. The premise, of course, is that freedom helps the poor much better than government. They couple this with a historic argument about how bad government has always been. So when someone complains about some problem with the free market, they respond that it may be flawed, but government is more flawed. You can dream of a government program that solves some problem, but history shows that government never lives up to that idealized version.
Of course, once you accept the premise that it is our burden to help anyone who needs it, it's just a matter of specifying the terms of surrender. If the free market can't be counted on to do it, maybe a little government coercion is necessary. So they don't exclude the idea of government welfare programs. They just bring some skepticism to the table. But at the end of the day, I don't know how that can stand up to something like "But think of the children!". It's the usual problem. Free markets may work well over the long haul, but what about the starving (or slightly less well off) people today? So they prefer a balanced approach that leans somewhere towards long term growth but is willing to make any number of compromises in the short term.
There are a number of places where there's no necessary compromise between the long term benefits of freedom, and short term altruistic benefits. Things like government corruption and waste, corporate welfare, etc. The biggest one is immigration. Open borders would have an immediate positive effect on the needy, and have a huge benefit in the long haul.
Overall, though, they're stuck in the same conundrum that conservatives are in. They want to argue for freedom and altruism, but when confronted with specific problems, freedom always surrenders. Who cares about long term growth when there are starving or sick people right now! And coercion is the only reliable way of making sure people give as much as you think they should. Freedom may be statistically better, but coercion is better in any specific situation.