You're correct. Unless a new interface could be invented, there's far too much friction in the idea, and like any network, it's value is proportional to the number of nodes. Unless all of a person's plans are in there, the value falls quickly.
It's pretty simple to see this - few of us even keep our 'formal' calendar up to date, of meetings, calls and plans. Very few people keep their 'informal' calendar up to date. I, for one, never create a task called 'buy truck', 'plan holiday'. The important, high value items never need to be written down. The ones that get tracked and remembered are the low-value ones like 'pay electricity bill' and 'pick up worming tablets for dog'. And they're the ones with little advertising value.
That said, there is probably a specific vertical niche in here that could be expanded, but more of an add-on to an existing network like facebook than a stand alone. Something like a 'holiday planning' where people could post a future plan like a trip to the Maldives, and have their friends (and advertisers) provide input on what to do while you are there.
It's pretty simple to see this - few of us even keep our 'formal' calendar up to date, of meetings, calls and plans. Very few people keep their 'informal' calendar up to date. I, for one, never create a task called 'buy truck', 'plan holiday'. The important, high value items never need to be written down. The ones that get tracked and remembered are the low-value ones like 'pay electricity bill' and 'pick up worming tablets for dog'. And they're the ones with little advertising value.
That said, there is probably a specific vertical niche in here that could be expanded, but more of an add-on to an existing network like facebook than a stand alone. Something like a 'holiday planning' where people could post a future plan like a trip to the Maldives, and have their friends (and advertisers) provide input on what to do while you are there.