I think it's worth noting what the WTS was teaching in 1992 that is now "old light". In the June 15th, 1992, Watchtower, it says that the dragnet symbolizes Christendom as well as "annointed Christians":
“So the dragnet represents an earthly instrument that professes to be God’s congregation and that gathers in fish. It has included both Christendom and the congregation of anointed Christians, the latter having continued to collect fine fish, under the invisible guidance of the angels…”
When I read the whole article, I was surprised that they gave a perfunctory nod to other religions for their preaching efforts over the centuries, even though the vast majority of 'fish' collected were apparently no damn good. But apparently that's not acceptable anymore and hence the change. I'm guessing that 99% of the Witnesses who attended the study on Sunday never even bothered to look up what the 'previous understanding' was in the first place.
Another thing that this article does (or more accurately, doesn't do) is address the problem of the 'separating' work. Regardless of when they say this happens (and I'm sure it'll go back and forth yet again in future articles), the jest of their illustration is that the "good fish" represent only Jehovah's Witnesses and even then it's kind of dicey as to who is classified as being "good". All the 'bad' fish apparently include people from all other religions as well as Dubs who have become slackers or 'apostates'.
If you take this illustration at face value, that would mean that only one kind of fish could actually be considered "good". Let's say a fisherman is out fishing one day and wants to get salmon. In addition to the salmon, he also catches some tuna, mackeral, shrimp, swordfish, etc. They're all in excellent shape. Would he really be dumb enough to throw them all back in the water simply because they weren't all salmon? Or would he be crazy enough to declare that only salmon can really be classified as being "fish" and all other kinds as being "worthless"? I sincerely doubt it.
Yet that is exactly what the Organization teaches today with regards to 'true Christianity'. Makes no difference if you're a Baptist, Catholic, Lutheran, Methodist, Protestant, etc. who lead good moral lives, are devoted to the teachings of Jesus, do charitable works, look after the widowed and the orphans, etc. You're not a Jehovah's Witness and therefore you are a 'bad fish' and worthy of being thrown back in the water.
I sincerely doubt that the average person sitting in the Kindumb Hell would ever think of this. They'll sit there, half bored, half listening, thanking God that they got their 15 minutes of Service in last month so they can be counted as "worthy".