I would like to ask you how you controlling channels and spammers there? In my classic server in Looking for Group channel there are only spammers who selling boosts through dungeons. However, this spoils the whole enjoyment of the game.
It is harder for players who can leveling their characters without any boosts to find group because this LFG channel is only BIG SPAM.
I can not also put more people to my ignore list.
Looking for Group is not a private channel so I think you should look there and starting to ban spammers.
There are addons that let you ignore more people.
If you want to filter for people that look for dungeons respectively you can again download an addon called puggle. It filters the chats you joined in a GUI.
IIRC that’s because the /LookingForGroup wasn’t in the game originally, Blizzard added it later with a patch, and for some reason never put it on the list of channels characters join by default.
It’s weird, agreed, but it still is an official channel.