"Allow direct messages from server members" is a setting you can control. You can toggle it per server, and also set the default for new servers you join. This

"Allow direct messages from server members" is a setting you can control. You can toggle it per server, and also set the default for new servers you join. This is more control than the IRC protocol offers - you can globally ignore all private messages there, or permit them. (You can also block individual users, of course, which you could also do with IRC). Private message spam is also a thing on IRC (though there it tends to be the "lonely women in your area" sort rather than crypto). This really feels like a social problem, not a technical one; and not one specific to Discord, though it sounds like you have encountered some particularly bad communities there.