Spoiler Chat Ingame

[ItMe]

The point would be so that I wouldn't have to make a whole new channel or revert to tells (especially if I was in an instance and couldn't). For those that especially don't use discord or anything like that having an ingame feature like that would be neat. Plus, (imho) linkshells and cwl do not hold a very large amount of people.

How many people would you be trying to banish to a late game discussion sub-chat that a new linkshell couldn't hold them all?
I don't think adding a spoiler sub chat would fare any better. Considering we can already make a chat for any purpose we want, and we can already just make one for late game discussions, it might be more prudent to ask that linkshells and the link simply be able to hold more members. That would also benefit every kind of chat and channel and not just spoiler specific ones.

The spoiler culture is so annoying and dumb.

On one hand, I thoroughly agree with you that spoiler culture has become needlessly extreme.

On the other hand, there's a big difference between seeing some spoilers and people actively and repeatedly discussing the later parts of a story you're engrossed in.
Trying to avoid such a situation is pretty understandable.