None of the streams I work with do. I’d be interested to see your metrics here. I actively advise the streamers I work with not to. I have even publicly told SE/SL/others recently and historically of bad development practices but nothing changes.
SLOBS aim is to take people away from the Twitch Dashboard, only problem is everything the Streamer actually needs is in the Twitch Dashboard, sure layout could be a little better and things could be tweaked to be better. But generally SLOBS is just wasting CPU cycles with the extra stuff being bolted onto what should literally just be dealing with Streaming. (Mileage may vary and people often see different results)
Don’t even need to join the channel you can send messages to a channel without joining. (This is the
g mode flag on IRC iirc, which Twitch doesn’t use, since it’s not IRC, just a note)
Personally if third party chat apps want to see this, a better option is for the third party apps to have a way that we can post data to them (as an extension dev) and it can be entered into events lists to be read, as not all streamers watch chat like a hawk for Subscriptions or tips. Custom Event alerts into SE/SL a better option than it getting lost in chat.
The problem there is how do you, the extension dev, know if a broadcaster is using SE/SL/Whatever, or want to consider/choose to supporting sending data out of a custom event hook.
This also needs to consider that if there is other data relating to the event, x picked this sound they paid y, they also left this message and picked this, but all of this doesn’t fit in an extension chat message so I need to put this in the events thread to the dashboard instead.
There are a number of things which mean using the Twitch dashboard is preferred. Even more so, now that panels can be popped out, streamers can just goto their dashboard, set their title, game, tags and pop open the config panel for your Extension, close the dashboard if they want and away they go.
End of the day using native chat rather than third party chat will always be better due to it always keeping up with any changes Twitch Makes.