This is one case when copying Sanders/Our Revolution and AOC/Justice Democrats is helpful and not divisive.
However it is also a politically convenient move by Warren. Supporting primary challengers for congress makes Warren look progressive. However there is no guarantee the primary challengers will actually defeat the incumbents. It’s a great PR stunt for Warren but might help with a few more donations for the primary challengers.
It’s not an “Incredibly Important Moment” but perhaps a sign of a “fake left in the primaries and run right in the general” campaign as the Clinton family pioneered.
Here is a video report of Warren’s ties to Clinton:
Here is a report of why she didn’t endorse Sanders in 2016:
Warren is a “team-player” with the Clinton Democratic establishment who cheated Sanders in 2016. Warren even flip-flopped on whether he was cheated or not. Warren has flip-flopped 3 times on MFA so far this year.