I suppose the "X didn't win, Y lost" is an awful cliche and bad way of putting it. The Conservatives self-evidently did win, and can and should enjoy the moment.
But there are signs I think that the victory is one created by a loss of a reasonable opposition. Labour lost the argument, not helped by sticking to the same team (or the same philosophy of that team) who lost in 2010. Not helped, either, by a collapse in Scotland of scarcely believable proportions. Both of these are issues Labour will have to address. And then the fall of the Lib Dems is equally dramatic.
The failure of polls to predict an outright Tory majority is somewhat balanced by their success in calling the SNP landslide. But perhaps this was where the Tory win came from. I've suggested that the reason there was a "No" vote to Scottish Independence was primarily because the polls briefly predicted a "yes" vote, prompting the sensible majority to turn out and vote for fear of losing. Here we saw polls predicting an SNP landslide victory along with an otherwise hung parliament. The first happened. Did fear of what it would mean for the second swing voters back to the Tories after all? Probably. Whether that alone accounts for the win is doubtful, as after all Labour wasn't winning even without that effect.
It's not spin, though, to point out that despite annihilating the Lib Dems, despite holding off the Labour challenges in key marginals, and despite winning an outright majority, the Conservative vote share has basically remained where it was in 2010. All those votes they tore away from the Lib Dems have just barely made up for losses elsewhere, to UKIp in particular. It's also not spin to note that the Conservative increase in vote share is less than what Labour gained (0.8 points to 1.4). Which makes Labour's fall even more dramatic, and their failure even greater.
And finally, it's not spin to argue that the SNP tide might well have swept all before it if only they weren't stuck in Scotland. How many more seats would they have won if they were standing in England? Probably quite a few. As it is, Cameron's only serious challenge in opposition still standing is stuck at never more than 59 seats.
With all their key rivals falling from grace, but with most of the lost votes from the Lib Dems effectively ending up at UKIP and the Green Party, the Tories still have some work to do in any future elections. 2015 will go down as a great Tory win, but it's a win that has a huge amount to do with the implosion of the opposition, and the redistribution of votes from parties that (used to) matter to parties that (still) don't.