ABLF disappeared, quite literally. Woke up one morning and it was gone, caput, and never heard from SSS again, despite efforts to reach out to him. There was no warning publicly, nor behind the scenes to us mods.
It's possible that someone "got" to him, but I tend to think not. We were heavily censured by proboards during the SJB (not CI user SJB) fiasco, and if that didn't run him away, I don't know what would.
Ignis Ardens shut down after the SJB fiasco. I'm not sure exactly what happened behind the scenes or if that was even the cause, though it seems likely.
ABLF 2.0, I know very little about. It did not retain either me nor tmw as mods, and was started pretty quickly after ABLF shut down, by Tradfly if I recall correctly. It attracted most of the Pfeifferite cultists that we banned from ABLF and Tradfly suffered their existence to a far greater degree than we ever did. I don't know why it shut down, but I would suspect that Tradfly just wasn't all that interested in continuing to constantly referee things.
As to the comment about "tadum" by the guest poster... you mean Te Deum? Te Deum never shut down. It underwent a restructuring of management and of focus to a certain degree, moving away from social discussion and mainly just talking about ecclesiastical things. Voxx started his own forum called "tradcath" and it is where most Te Deum users have gone for more socially-oriented discussion.