Ditto what IO540 said.
In fact the OHJ requires more faffing around in the circuit and more risk of collision (in this incident, an OHJ would have done nothing to avert the risk by all accounts). At least if you join on say base leg, you can get a picture in your mind of the traffic and there should be only two directions traffic will be approaching from, downwind or final (for someone on a straight in).
Approaching from the deadside then the crosswind join (as in over the numbers) is the most expident way to join. You can also modify your flight path to the left or right to fit in behind someone else in the circuit quite easily.
We fly extremely tight circuits where I am based due to noise abaitment.
Anyway, a sad day and a sad needless loss of life.