Even with newspapers and the like are filter bubbles possible. I am free to buy only the newspaper who writes the stories in the way I want to read them. There are left wing newspapers and right wing newspapers and stuff in between. And even with newspapers and broadcasts you are still free to only consume what you want to consume and block, by not buying or active ignoring, what you not want to see or hear. Things like cracker-barrel philosophy or Stammtischparolen where a thing long before the Internet.

Are you arguing that the filter bubble effect is the same for a newspaper and for a social media site?

Yes, the filter bubble effect is still possible to some extent with a traditional chronological news feed, but it's quite frankly absurd on it's face to claim that that is the same severity of filter bubble, when a site like Reddit / Lemmy operates by taking those chronological news feeds and filtering them further.

The Guardian might be a relatively true neutral newspaper (meaning it appears to lean left by mainstream standards), and yet articles it publishes that back up any remotely right wing / economically conservative points do not get posted here.

Echo chambers naturally arose in the past because information could not travel freely, that does not mean they are a good thing or something that we should be recreating and reinforcing on the internet now that it can.