What strikes me particularly odd is the fact that this forum is extremely well-known amongst PhD students. On the other hand, it is extremely well-known to those professors who regularly advertise PhD positions on the sister site.

Nevertheless we rarely ever hear any views from actual supervisors! So if one of them reads this, get out of the shadow and talk about the PhD experience from the other side. I'm sure loads of supervisors are secretly hanging around on here. Or is Shani in reality a supervisor?

Perhaps there is some sort of apartheid between students and supervisors I wasn't aware of? But if there is, I don't see why this forum could not benefit from the contributions of advisors.

"or is Shani in reality a supervisor?"
LOL you made me laugh! What made you think that? Or are you being ironic, erm, were you thinking "who would be the the least likely to be a 'secret' supervisor, due to being overly dumb?"...
I can assure you that I am a very normal, unfunded, struggling second year PhD student. Well... some of my friends and me, we do discuss our work together a lot. Sometimes it feels like they are my real supervisors and I am their's, as we sometimes give each other more advice and time than we get from our sups.
But your question is valid. Are there any supervisors lurking on here? Now is the time for your coming-out!

Mine will read the forum over my shoulder and offer his two'penneth. He has so far resisted my exortions to sign up because he thinks it will eat into his time.