We're used to a world of such clear division and fighting between the 2 parties: democrats and republicans. But, The irony here is that it's democrats that are threatening to break up facebook and yet facebook is deeply democratic/liberal.
After their 2016 electoral loss, the Democratic Party huddled up to develop their "Better Deal" agenda, to explain what they would stand for, should voters return control to their party. Antitrust was a huge plank in that platform. https://www.vox.com/policy-and-politics/2017/7/31/16021844/a...
That said, perhaps a segment of their base would be more energized by attacking large corporations. Appealing to an extreme wing, and using that strength to create broad enthusiasm, worked for their opponents. I used to believe that if you were forced to appeal like that, you couldn't possibly get enough votes from the center, but my intuition appears to be in error.