G+ had a few things going for it that gave it a strong TTRPG presence. The first were distinct community forums you could contribute to and see in your feed using one login. the second was Hangous as mentioned by @Forrest. The third is that as a centralized social media platform, cross pollination between communities happened as folks added each other as individuals and saw posts from both individuals & communities.
This had the benefit of having focused communities that could curate memberships and have discussions related to their focus, while still having a open common space for general chat. This meant that the entire platform wasn’t dominated by a single personality or brand that the platform the brand was built upon. Google + was the service, but not the product as it were.
The downside of that was that once the service lost new engagement, & new advertising data to sell to other companies, it lost value. Since the space was owned by a corporation that had no vested interest in TTRPGs as a product or community, we lost that platform.
The biggest challenge at the moment is that it’s hard, really hard for creators to make a living wage working in tabletop. Either you get a salary from a Big Brand, or you bust ass as a freelancer & often get shafted (there’s a lot of horror stories about this) or you’re an independant creator, making games, or zines, or a podcst, you youtube vids, or streaming, or blogs. The community’s not big enough to make ad revenue work for any but the biggest names, so it falls to either selling games & merch or crowdfunding to support creators.
For the crowdfunding or sales models to work, creators often have to build communities of their own, or become a prominent figure in an existing community. With communities scattered to more isolated platforms like Discord channels, cross-pollination is much rarer now since we’re not all in the same ‘place’ sharing a common public platform.
The Gauntlet Forums are totally free and public, and there are lots of great users from the Gauntlet community & it’s growing fast. Gauntlet is a great place for discussion on a great variety of games, & a lot of original content through the paid zine Codex & the free podcasts.
The Itch forums have an opportunity to grow and be a direct connection to a lot of game creators, & I think it’s going to have a big part to play as well, but a totally different focus to Gauntlet.
Private spaces also have their role to play as well, allowing for folks -especially marginalised folks- to curate their community, & have discussions where they don’t have to be publicly ‘on’ for a wider community.