Nope. If anything, there is past precedence from the 2001 Antitrust case against Microsoft [1]. Note in that case, it wasn't about whether consumers were directly harmed, but whether Microsoft was abusing its market power to prevent other entrants into the browser space. Arguably this is very analogous to what Google and Facebook are currently being accused of.
[1] https://en.wikipedia.org/wiki/United_States_v._Microsoft_Cor....