I don't want to be too snarky, but is this news to anyone? Who is building start-ups that are trying to be everything all at once? Who has that many resources?
My company has a niche software product and we have people contacting us all the time who love it, but find it missing just one feature to get their business. That feature may happen to be extremely difficult to write or have limited use to our core customers. But if this is a large company or a lucrative contract then it can be very difficult to resist. There may be times where, financially, you really need the income. It could even mean the difference between staying in business or not. So, it is not always so cut and dry when you're in the middle of it.
Was working with a client trying to get a narrowed focus of that 'one thing' to latch on to, vs the "this tool will do ABCXYZ for all working people". We got to the point where, when imagining potential users, there were more people who were not a fit than who were a fit, and things picked up after there. Suddenly there was one problem that was being solved for one particular type of person in one industry, and it became easier to focus everything else around that.
I think what articles like this me is that the author/company has 'figured it out' through their own experiences and are so excited to share that joy in some way.