While they were equally at fault, or equally innocent, I think it's fair to say a more experienced driver who'd raced Hockenheim more wouldn't have put his car in the position Magnussen did. You can't lunge up the inside there due to the way the track pinches in on itself - you'd have to be level with the driver on the outside to have a fair shot at going through. While Magnussen didn't lunge, he was just sat on the apex - he should have just slotted in behind Bottas.
It was completely and utterly Massa's fault.
Massa was unwilling to accept the idea someone might be on the inside line, he started on the outside, you can't just turn in when someone else is going to be there. He positioned himself wide and for the start of the race at the very least you HAVE to assume someone is going to be on the inside.
Massa simply never does this, he has a now very long history of simply turning in because he thinks it's okay to, even when he's turning right into the path of another car.
http://www.bbc.co.uk/sport/0/formula1/28391518
watch this video, at 12 seconds in Magnussen's front wheels are IN LINE with Massa's front wheel. Massa is on the outside but has decided to go across the apex even though he was on the outside going into the corner. Magnussen DID brake, and hard, which is why the contact is a little further back on Massa's car, he turned across him completely even though they were alongside each other.
At 13-14 seconds in you see Ricciardo(I think) on the outside of Vettel(I presume) and the line he takes is the sensible "outside" line. The two cars went in alongside each other through the corner. Ricciardo both having a car on the inside and starting on the outside made no attempt to take an overly tight line into the corner. Massa's absurd attempt to cut the corner tight at the start of the race when there is every reason to believe there would be another car there. It's insane, not least because the guy on the inside because he can't take the usual line, which would be flooring it and moving to the outside, has to go slower and turn further before putting his foot down so the outside will get power on first and harder and have the better exit from the corner. Massa is 100% at fault for that crash. I think if you watch 3 separate pairs of cars go through that corner alongside each other only Massa attempted such a tight turn from that wide out.
He's either incompetent or he purposefully drives in to people assuming they'll back out which is incredibly reckless and nasty driving, well the other option is he just wanted to smack him off but I don't believe that.
He has zero positional awareness. Go back to the crash in to Kimi. The car ahead of Massa that had less time to react managed to go around the left side of Kimi, with Kimi moving in his direction and with all the grip of being off track, made it around without being hit. If Massa simply moved to the right side of the track he would have finished that race(or more likely smashed into someone else further into the race), the only reason he hit Kimi is because he randomly smashed on the brakes and lost the rear end of the car.
I can't even explain how a supposedly top driver decides to lock his brakes while trying to drive around another car. The fact is there was a crapload of space for him to avoid Kimi completely and only driver error caused him to hit Kimi, entirely avoidable on his part and he screwed it up.
Massa is fast becoming this years Maldonado/Grosjean, hitting anyone and everything with insane driving.
That he has "called for cooler heads on young drivers" is absurd. As some of the rookies have done some of the best driving this year and Massa has made the most mistakes.