This assumes all conversation is equal quality. That particular point has never been true in social media, and has actually become worse post-2016, with increased partisanship and bad faith arguing.
It's impossible to run a high-quality discussion forum without some sort of check on bad behavior. That said, it's up for debate whether downvotes are the best answer to this problem.
Secondly, there are two solutions to that problem:
1. If you believe the environment, group, or social body of a particular conversing venue is heavily biased, whether deliberate or not, you don't have to participate there. Simply leave.
2. If you believe a particular user is deliberately exercising some form of bad behavior or displays an inability to follow the conversation you don't have to reply to them. Simply let it die.
For example: whether or not I ever liked or voted for President Trump I would never spend time on Reddit at r/theDonald because I know conversation there is biased like a form of cult worship. Why bother conversing where you are not allowed to disagree on any matter?
I remember pointing this out once on Reddit, before I deleted my account there, and it temporarily changed peoples' behavior resulting in more replies to disagreeable comments in either r/javascript or r/programming (I don't remember which). Most of the justifications that arose from down voting without a reply, supposedly a silent and anonymous form of disagreement, all summarized down to excuses about how writing anything takes too much time or a user's an inability to write an original comment. But then, in those users defense, Reddit feels like such an echo chamber.
https://www.logicallyfallacious.com/logicalfallacies/Appeal-...