Discord forces libraries devs to do caching at the ground level as Discord is fundamentally different in how it functions that the library has to implement caching or the library ceases to function.
Twitch library develops don’t tend to implement this as a lot of Twitch bot libraries don’t even call the TwitchAPI for anything as they connect to chat.
If the bot needs the display name of the user running a command (instead of the username) it’s in the tags of the chat message.
If a bot needs to check if the user is a moderator at the moment they ran a command? It’s in the badges in the tags of the chat message.
Most of the information, pertaining to a user, that a bot would ever need, is sent with every chat message. So a bot doesn’t need to “waste” resources caching it.
If your twitch bot needs to go get the Title of a channel, then you would develop a secondary service that consumes Twitch webhooks. Or the bot itself would go fetch and cache it itself internally, at the choice of the developer, if the bot has a !title command
Discord has a defined set of things that should be cached.
Twitch does not as every bot is different or doesn’t need to
No Discord is not IRC compatible it’s a totally different protocol and communication method.
Running Discord bots myself I’m somewhat familiar with the differences. Even if I don’t run bots that operate in more than one channel/guild generally