Funny you should mention that, it's happening at AV and EN now. But it's still funnelling multiple aircraft into these navaids, there's not enough of them for an outdated training system that matches an outdates airspace system.
And the airprox events are happening over Avalon despite having class E down to CTAF due to the amount of aircraft using it on a good day. RADAR control is a predictive device, it struggles when the dynamic situation is changing rapidly, and then there's the delay in relaying the information to each aircraft. Add to that the issue with monitoring two frequencies as well as flying the aircraft in busy airspace and the chance of holes lining up is vastly increased. If it's just IFR aircraft then you have no issue, as they can all be lined up in a nice sequence and it's done. Throw in a few VFRs that just ramble across the approach paths and cause go-rounds and you start getting mayhem and radio congestion.
It's also important to remember that the radar plots had the two aircraft missing each other, it was a proximity alert that came up on the radar screen and showed JQF passing behind AEM, and then under it by 500ft shortly before the collision.
The other issue that really is at the center of the whole IFR training thing is why are NDB still a thing. All these VORs were shut down at various locations to leave the worst possible backup, showing that cost really does come before safety.