I get the argument, but email is also very different to the kind of open-web network that the fediverse resides in. There are problems the fediverse faces which email doesn't like discoverability. The emails either come to you or they don't. With federated social media, you have to find the content you're looking for first. Maybe you use a search engine, or somebody gives you a business card with their handle and instance, whatever. Then you have to figure out how to view those posts from your home instance if you want to actually interact in any way. There's browser extensions and stuff which try to make this easier, but that's another thing that has to be explained and set up, plus not everyone is visiting from a web browser with extension support, or a web browser at all for that matter.
It's not fundamentally impossible to understand the fediverse, but there's more of a barrier than email, which can be explained in a single sentence like "Your email provider gives you a unique address that anybody else can send emails to and vice versa." I don't think convincing ourselves that the fediverse is actually very simple is going to convince people outside the bubble that that's true.
There's not really any one reason the Dreamcast failed, but the library being larger doesn't necessarily map to the library being better. The Dreamcast didn't have any heavy hitters on the level of a Mario 64, Mario Kart 64, GoldenEye or Ocarina of Time. In terms of games that are still in the mainstream consciousness, it's probably Sonic Adventure and Shenmue.
The library also had another thing that I think held it back from greater success: ports. Releasing so early, basically in the middle of the lifespan of the PS1 and N64, meant that a lot of the games were cross-platform with one or more previous-generation consoles. It's hard to demonstrate the power of a next-gen console when so many of the exact same games also worked fine on the consoles people already owned.
The other big source of ports in the Dreamcast library were arcade games. Sega was offering the ultimate in home ports of arcade games at exactly the time in the games industry when arcades were collapsing. The Dreamcast was the best way to play basically any cross-platform game that came out in that period, whether it was ported from arcade or lesser consoles, but ultimately they were games you could already play or that you specifically didn't want to.
I don't want to give the impression that the Dreamcast didn't have good or original games, it had both, just not "I must upgrade my console mid-gen"-quality games. It's a library that's aged very well but at the time, not enough people wanted what they were selling.