The unique selling proposition of SaaS services

There is such a book in Jeffrey Moore, called "Inside the tornado." He talks about strategies to conquer markets. The main idea is to conquer the first niche market by creating a holistic product. For example, Directum first delivered applications for the pharmaceutical industry. And then I went to the adjacent markets, and then I became the technology leader. The main idea - at least for a small niche to create a complete product. This is called a bowling alley strategy.
I remembered this in connection with my recent discourse on the topic of the problems of SaaS services development (in my blog). But really, I do not know of any SaaS service that would provide a holistic solution for any niche.
In my opinion there is only one way out - to turn to face specific consumers (no matter how trite). You cannot sell your solution to the entire market. Because you have no such decision yet. Learn to serve at least a small niche and become a leader in it, having solved all the problems that have arisen along the way. There is no happiness in the SaaS model itself, there is no happiness in the new-fangled project management system, there is no happiness in online. Happiness is only in solving the problems of automation of a particular company engaged in a specific type of business. Then they will have real savings on IT and a real reason to use the services.
Why is there a bunch of SaaS services that automate task management, but not a single company that automates, for example, the catering business?
But who buys the software? Business. Do not project manager. And then everyone wonders why SaaS is growing slowly)
Nobody cooks soup))) Everyone sells potatoes in unpackable packaging.