Reddit is the old internet.
Ehhh.
I'd timeline it something like this:
Interaction was on non-Web-based systems, mostly distributed
This was mostly pre-2000s and tended to go into decline in the 1990s or 2000s as Web-based platforms focusing on ease of use picked up users. Many of these were distributed.
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Usenet (decline as a discussion forum dating to maybe late 1990s, though lots of pirated information is still transferred via it)
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IRC, peaking around 2003 according to WP
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Email (peaked later, in 2009, according to WP. Obviously still pretty healthy compared to the above two.
People tend to shift towards interacting with each other on large websites; these tend to later acquire mobile apps to cater to smartphone users.
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Facebook
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YouTube
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Twitter
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Reddit (though a fair number of third-party clients did exist)
If the Fediverse manages to pick up a lot of people, it's probably somewhat-closer to the first phase.