Why have they stopped private chatting?

So like in they used to private chat each other often, but for some reason they have stopped doing that and I was wondering why? I didn't really think of it that much but I just watched the video of someone doing a unstable universe rp as a joke, and they said "pretend that he's private chatting you because they used to do that" and that actually got me thinking I've realized in more recent videos they don't private chat anymore, do you know why they stopped? Is it just for more immersion or something lol

It's obviously not a big deal at all but now I'm kind of curious :]