Facebook looked so set to be the winner amongst social networks that it took what looked like a logical step to cement itself as a platform - become a platform and encourage third party software.
The problem is that it has become a platform for an endless sea of horrid little gimmicky crap that makes Windows shareware look like SAP, and irritates you like a viral infection in the endless arms race to go, well - viral. This is a major cockup since it goes straight to the core of what Facebook had going for them. Facebook had a UI that was actually professional, whereas Myspace was by its very nature gimmicky crap.
Even as Facebook will almost certainly correct itself, some of the damage is already done. With a decline in growth at a time when they are still much smaller than Myspace, their march to dominance will now never be as pristine as Google’s, and some of that decline is surely due to the fact that Facebook has become kind of annoying due to the application platform.
The fault of the failure of Facebook platform of late, is due to the platform itself, not the apps, to say otherwise would be to blame the tools rather than the workman. Because Facebook’s precocious founder, Zuckerberg claimed that the Facebook developer platform would change the world and he had the audacity to snub the likes of Google as recently as this week over access to the API, this is a failure that competitors will probably never let him forget.