Regarding X, I still see plenty of left-leaning content, but the dynamic has undoubtedly shifted. What’s changed is that the platform no longer artificially amplifies one ideological perspective at the expense of others. Previously, algorithms seemed to prioritize content aligned with extreme left narratives while outright blocking opposing views. That system gave the impression of a dominant left-leaning consensus, that was entirely artificial.
At the end of the day, it's impossible to remove all bias so whatever system maximizes free speech is the best one.
Also, it's just not true that "Previously, algorithms seemed to prioritize content aligned with extreme left narratives while outright blocking opposing views". It's a lie. Twitter's research itself revealed their algorithm favored right wing politics even before Musk. And it became a lot more true since he took power. See: https://www.pnas.org/doi/10.1073/pnas.2025334119