As far as I can tell, Discord doesn't delete history so you can join an older discord and scroll back. 99.99% of slacks that are free lose history after some arbitrary timeframe (used to be 10,000 messages, now I think its 90 days). Plus you can connect Discord to your Steam/Playstation/Xbox account, which gamers like.

Relatedly, the "gamer-oriented" business model of sell cosmetics and subscriptions to every user individually rather than the Slack big enterprise-oriented business model of a central admin paying an entire per-user cost out of pocket was a factor in many of my communities moving from Slack or skipping Slack. It's a lot easier for a small community admin to start for free and find enough "Boosts" from community membership for the nice-to-have server features that cost a bit extra than to foot the entire bill themselves in the hopes that enough users will eventually reimburse them. (It also allows for a hybrid where a community admin centrally pays for some amount of boosts, but doesn't have to pay for all of them.)

> 99.99% of slacks that are free lose history after some arbitrary timeframe (used to be 10,000 messages, now I think its 90 days).

This is exactly the reason cited for several non-gaming discords I'm in.