I think I’m inclined to agree about bot spam in chat being primarily noticeable in smaller channels. If the channel I frequent more often had 600 concurrent viewers instead of 60, I may very well have different priorities in this discussion.
If twitch’s response is going to be, “Well, channels with less than a few hundred concurrent viewers aren’t really worth our time for this issue.” Then that feels bad but at least I understand it.
But even discounting the block and report tools, I feel like we have some mechanisms by which we can make inferences about the value of whispers being sent. I think the first and most important one would be verifying that there are one or more channels in common between whisperer and the person being whispered. While it’s possible that a spammer could get around that by joining a channel, spamming the viewers then leaving and joining a different one, there are ways to account for that. Looking at how long they’ve been in a channel’s list of chatters would probably be telling. It may also be worth checking if the whisperer is a mod in the channel(s) they have in common. Certainly not all bots are mods in their channels, but some certainly are and it seems like it might be meaningful data. It also seems unlikely for a single username to both be a helpful channel bot and a dastardly spammer. Once you can put a bot into one group or the other, you likely don’t need to check it as frequently. And while these checks sound computationally and temporally expensive, random sampling is probably your friend.
Again, I don’t know, I’m just some dude on the internet. I’m sure the twitch developers are a lot smarter than I am, and I feel like the odds are good that they could come up with something if it were important to them to do so.