I've been observing the creation, expansion, and slow heat death of Reddit for a long time now (had accounts there since it opened). I think that Reddit's decisions here accelerated a decline in content quantity and quality, but the trend had been happening for a while.

I think that the biggest issue behind this decline is infrastructure based. Reddit was designed around the basic concept that the desire to post and contribute to the discussion would be reward enough to drive participation. Karma is the point system for this participation, a number that only speaks to popularity, not the quality of a post or a contributor. When the community was small, this non-specific variable served the purpose of identifying content trends, but karma is very poor at describing WHY a post or comment is popular. Eventually, instead of karma being an indicator that someone had contributed to conversation, it's only meaningful metric became one of popularity or notoriety.

This meant that where once Reddit had been a haven for enabling discussion on any topic, it became a shouting match between who could get the most upvotes. This cultural shift became very apparent after the Digg exodus, and the trend accelerated as other social media copied Reddit's voting and karma system. Of course, Reddit began feeding off of their content, which was also popularity driven, and once the content algorithms started coming into play in the mid-2010s, it created a feedback loop of popularity driven schlock that drove most real discussion to fringes of the site.

We've recently seen this dynamic start to even affect Google, whose search results are getting hammered due to Reddit's blackouts, and whose search results have been significantly dropping in quality over the last few years.

As for myself, I still browse certain reddits that I haven't found equivalents for in the Fediverse, but it's pretty clear to me that Reddit's not really a positive place for contributors - whether they be moderators or posters. To some extent, I'll miss the reach of Reddit's audience, but lets face it, most of that audience is just shitposters and bots.

Will the same trend happen in the Fediverse? Possibly, but I think there's more potential here for positive change than there ever will be in a company led by the likes of Huffman, or for that matter any company or centralized authority. Besides, it took about 15 years for Reddit to condense from being a cool place full of new ideas to the condensed black hole of regurgitated shitposting it's become. I think the Fediverse has a bit more potential longevity than that.