Does leftism mean rejecting everything that is true and believing what is untrue?
Yes, but indirectly.
Leftism gets to "Untrue" by hiring, promoting, and encouraging people who are "Stupid, Immoral, and Incompetent."
No, just as conservatives don't walk in lock step, neither do those on the left. However, there are core values that a side, almost in it's entirety, believes. To illustrate that there are outliers, I just read about pro-life democrats (re: DFLA). Who said pigs can't fly? LOL!!
The reality is you can tailor the MSN newsfeed on your desktop to exclude or include articles from specific sources. I’m not sure it healthy to always only read things with which you agree. It is good to know what the other side is saying.