There is no such thing as "coincidence" in accidents like this. There is obviously a loss of situational awareness at the heart of this accident, easily avoidable with proper procedures but as is often the case at this end of the aviation spectrum, way too common for comfort. To simply shrug one's shoulders and say "there will always be accidents" is to be way too accepting of lax standards and procedures. If airlines thought like that, there would be a lot more accidents than there are - but most airlines refuse to accept unnecessary risk in their operations and actively seek to eradicate as many holes in the "swiss cheese" as possible.
Yes, I have had a few close calls over the years, but pretty much all of them were while instructing. They range from the standard lack of situational awareness (ie being cut off in the circuit) to people who thought it would be fun to formate on me without my knowing they were there, to encountering people in Low Flying Areas who weren't talking to anyone while fanging around at 50 feet with no regard for legit training traffic.
Even recently, I spotted one guy who, despite numerous traffic calls from me, drifted so close I had to take avoiding action. He had clearly not seen me as he bimbled along, and shortly thereafter he gave a position report that was out by over 15 miles. Scary.
There is a lot of dodgy stuff happening every day in the flight training world, it's about time it was recognised and dealt with.