I only vaguely remember Indymedia from the 2000s. Mostly at that time I was doing other things with robotics, but when I started running a server in 2010 there were still some vestiges of it around. In the 2000s especially after the start of the Iraq war there was the general belief that the mainstream media was rotten (it still is) but that it could be replaced by what was known as new media - meaning grassroots internet sites such as blogs and podcasts. It's now far less clear that top down mainstream media narratives can be successfully countered by what little remains of the independent internet, but it's an ongoing site of struggle.
A podcast here describes some of the reasons for the eventual demise of the Indymedia project. Some of the backstory is that from the late 2000s onwards unencrypted http-only or minimally https sites were beginning to get actively hijacked with script injections and session token stealers, or have login credentials intercepted (firesheep, etc). In that time frame TLS certificates were expensive and difficult to install, and that's the reason why self-signed certificates and SCARY browser messages were common. LetsEncrypt eventually negated that problem, but it remains a possible single point of failure for a large number of independent sites. Imagine what happens if LetsEncrypt goes away.
Another related video here.
In the middle of 2019 I thought that ActivityPub was a failed protocol. Now at the end of the year having written an ActivityPub server I'm more optimistic about its prospects in the longer term and its ability to resist attempted usurpers even while having less than ideal advisory privacy and unspecified authentication. Between being provably mathematically secure and entirely lacking transport security there's a grey zone where things can be "good enough" against most adversaries most of the time.
New media is certainly needed. You only have to see some of the mainstream election coverage in the UK in December 2019 to easily observe how absurdly biased it is. There are things like Novara - which is arguably the most successful independent media project of recent times - but they appear to be being slowly assimilated into the parliamentary circus. Merely having independent websites isn't enough, but it's a prerequisite for doing something different.