Yes, the browser-based clients is something I don’t like either. I loved when Slack used to provide an IRC interface so you can use whatever simple client you want.

But the syntax highlighting is so good on Discord, that it makes it really easy to discuss technical stuff.

I would jump on a chat alternative that:

    • is Google searchable (like Gitter)
    • has good syntax highlighting (like Discord and Slack)
    • has CLI clients (like Mattermost)
    • has a low barrier entry for non-technical users 
        • sign in with Google
        • state your issue
        • get solution in a few messages
        • forget about it if you don’t need to be part of that community

Conversations are locked inside Discord the same way conversations are locked inside IRC, it's a community chat rather than a knowledge base/QA like stackexchange.

Correct me if I'm mistaken but logs of public IRC servers are often available without needing to make an account on IRC, right?

You're mistaken, that's a channel by channel basis not a server by server kind of deal.

Some channels include bots used to create public channel logs, but not all. Creating unauthorized public logs is usually considered against IRC etiquette so many channels go unlogged.