This article is incorrect.

1 - Lots of apps don't solve any "problem". Lots of apps don't sell anything other than ad space. Some of them succeed

2 - Lots of 'Apps' can be successful with one founder. Perhaps this writer means "startups"? I'd say most entrepreneurs would rather go it alone than make a bad founder choice.

3 - Sometimes all you need is to remove a single pain point to be a world apart from your competitors. Whatsapp was just another messaging app. But it made it easier to find your friends, by using your phone number and contacts to quickly 'seed' your network. Boom.

4 - The one valid point. If you can't explain it to someone, how do you sell it?