I think it's more due to political ignorance and the overton window shifting right the last 50 years. People tend to equate modern liberalism, which is very much pro-markets and pro-capital, with leftism.
It’s not an echo chamber to refuse to accept hate speech and shitty right wing media. It’s an interesting but continuous claim that if you don’t accept far right and increasingly fascist viewpoints, you live in an echo chamber. This is a lie.
Basically what I did is just follow some people I knew from twitter, and from that I discovered a few follow lists and block lists that I liked. Within a couple of days I had a pretty well curated and very busy feed of things I was interested in seeing and interacting with.
Bluesky definitely has a "this is what twitter used to be vibe" but it's so much more than that. With follow lists and block lists it's really easy to get up to speed and curate your feed. It's also very noticeably less algorithm driven.