People working for Google, Facebook, and Twitter are smart. They understand this and have used the argument of being just infrastructure in the past. They had

People working for Google, Facebook, and Twitter are smart. They understand this and have used the argument of being just infrastructure in the past. They had to switch their story because they are not a neutral carrier. They prefer some messages over others. This is linked to their revenue model. The simplest solution to 'just be infrastructure' is to show all messages linearly. A more complex solution with possibly lower revenue is this: they could let the users pick algorithms to filter and sort the content, then they could claim to be infrastructure again. The user would need to be able to inspect the algorithms. The simplest one would be: no sorting, no filtering. That would make the sites unpleasant. The smart people at Google, Facebook, and Twitter must have considered this option but decided that it is more profitable to share the power over what people see with the regulators than to share it with the people.