Finlay Malcolm and Chris Ranalli had a paper published in March, concerning what's so bad about echo chambers? The article was published in Inquiry: an interdisciplinary Journal of Philosophy;

Abstract
Echo chambers have received widespread attention in recent years, but there is no agreement over whether they are always epistemically bad for us. Some argue they’re inherently epistemically bad, whilst others claim they can be epistemically good. This paper has three aims. First, to bring together recent studies in this debate, taxonomizing different ways of thinking about the epistemic status of echo chambers. Second, to consider and reject several accounts of what makes echo chambers epistemically harmful or not, and then offer an alternative account which builds on some features of existing accounts. In our view, echo chambers – even those that are truth-conducive – are always epistemically harmful because of their reasons-undermining features, e.g. the way that they impede the development of epistemic reasons which can answer and withstand challenges. This account captures important ideas behind several theories in the epistemology of echo chambers, but offers a richer explanation that does not suffer from their limitations.