1. The Filter Bubble. The idea that you can be shut in your own bubble, not being exposed to new ideas or ideas that contradict your own, is pretty bad
2. The idea that a for profit company becoming the arbiter of truth ( with noble intentions of fighting 'fake news' etc ) is also pretty bad. It can be used for political or economic gain
3. The company has a largely hostage users that they can abuse through predatory pricing etc
The opposition is not towards technology, but towards one company controlling most, if not all, of modern technology