Yep, that's what is said when saying "Facebook [...] kills democracy for their own benefit". They provide a discourse perceived as the public discourse for a profit.
Some people are considering that this exercise is a threat to democracy, and even though you seem to imply that you are more versed / cynical / aware ("Give me a break"), that's precisely the for profit part that ruffles some feathers.
> What kills democracy is people incapable of convincing others that they are being mislead/wrong without insulting them with all possible -ism .
Offering a platform for misleading news does not help and actually plays an active part in this.
> What kills democracy is people on both side being so extreme they just can't talk to each other anymore. Facebook isn't responsible for that.
Building a bubble is the prime example of how you can stop separated communities from talking to each other. You can say that the separation existed before Facebook, before other online communities, it does not make it any less salient that these bubbles exists and that it is in the monetary interest of Facebook to further them in order to sell better targeted ads. They whole business plan, their whole point of existing is depending on practices and behaviors that are currently a problem in our democracies.
This means that as of now, Facebook will fight for these problems when they fight for their business. Even if you don't use Facebook or other social networks on the Internet, this means that as an individual citizen your country / nation is being influenced by these products. Even if you choose to not use them, it is perfectly reasonable to go out of your way to tell people to stop using them and to fight their influence in your country.
So, people can perfectly continue to blame Facebook for these problems. No one says that they should be alone in being blamed on this, no need to exaggerate the critics to make them appear ridiculous. But acknowledging these problems is absolutely critical these days.