The point is that a few large companies like facebook, amazon google and some more, are collection and analysing data at a massive scale. The data collection goes way beyond providing a better user experience and that kind of stuff.

Putting such information in only a handful of companies can prevent us to make well informed decisions in many ways.

They are hard to avoid either. Even if you're not on Facebook they are still mining metadata from WhatsApp. The app is closed sourced so we don't know how well the signal protocol is implemented or maybe is modified.

Yes, there are great alternatives like Signal for that but the problem is that you need to convince everyone to switch to apps like Signal, which is hard because most people just don't care.

Those big companies are a poison for sure if you'd ask me.