I know This post talks about it, but I'm posting for two reasons.
1) It was posted nearly 4 years ago
2) That question only covers a ping for idle users
I know that pinging could be quite annoying for some, so being able to be pinged would probably have to be toggalable. It could be some sort of notification or noise. It would only work if you're online
Alternatively, add some sort of quote feature like discords so you can reply to posts better, which is the main reason I want pinging in the first place.