Tech companies in particular have very concentrated employee bases - there is a lot of incentive to grandstand against them if your constituency doesn't get many benefits, especially if that constituency comes from places that don't have much in the way of technical literacy.
Still, breaking up any company for being too successful is a great way to keep your economy from growing. I don't imagine sane politicians will actually follow through, especially since breaking up trusts in the past did almost nothing to help the consumers it was supposed to.