Democrats who voted against aca in 2010 but still lost the seat. Why?

[Never]

So going back to the original question

Did democrats lose because democrats didn't come out and vote for them?

Not necessarily. I suspect that Republicans and Republican-leaning Independents were so motivated in 2010 and were unwilling to differentiate between Democrats who did vote for Obamacare and those who voted against it. While Democratic turnout was poor that year, that only partially explains why so many Blue Dogs lost.