While the article is a bit over the top it does raise a valid point of companies desperate to add more value, essentially destroying the value proposition for their most loyal users over time by actually creating negative value in the form of features that no longer work, annoying features, redundant features that distract, etc. That definitely happened to Dropbox, Evernote, Flickr, and quite a few other former "unicorns".
I have no use for Dropbox at this point in my life. Once upon a time I used it and I even considered paying for it (but didn't). But at this point it's a commodity that does not solve a problem I have and is not worth anything to me because I have better alternatives that are also freemium. If I want to share files, I have multiple zero cost options that will work without too much hassle.
My theory of software is that over time any good feature either becomes a commodity thing that adds negative value if you do it poorly (or fail to do it entirely) but does not add value if you do it well; or a niche thing that costs money that nobody cares about enough to do well for free. Usually the cheapest way to do those features well is through open source. You have to in order not to differentiate negatively. OSS is this pacman thing that gobbles up all good things in software and converges on a best possible implementation for those things and provides it for 0$. You can pay to make it go faster, for support, for convenience, etc. But the basic feature is there forever in the form of good old, free speech, OSS. And if you don't like it, you can grab the code and fix it. All good software is doomed to become a commodity.
The vast majority of things people care about ultimately end up being grabbed by one or more OSS projects and replicated. The UX isn't always great. But you can get the thing for 0$ and it will work and it will have a commodity of people nurturing and caring about it. If you are smart, you can build an entire company without ever buying any software. And many multi billion $ companies exist purely to act as a convenient facade for open source. Convenience is worth money. Features are not.
So-called unicorn companies are not based on value creation but on using investor money to "get there first" before the window to do so runs out. Timing is everything. So, you get rushed, easy to copy products. As soon as the investment happens, a dozen competitors get funded as well and typically ship competing products within months. After that the OSS pacman catches up if the thing is at all relevant. The problem (for investors) with that is that the window inevitably runs out and it is short. Also, most of these companies are one trick ponies that never had any IP worth protecting long term. So, the value payoff needs to be huge or there needs to be some kind of moat that stretches the window.
Basically, Dropbox is similar to rsync with a UI and a not even a particularly fancy/good implementation. So, as soon as there was a hint of success, people copied their rather trivial feature set and from then on it was a race to the bottom in terms of pricing. The ultimate of which is of course 0$. Such is the fate of all good ideas in software: they get copied.
Dropbox built a commodity and the obvious things happened. Copying files over a network was a solved problem long before Dropbox existed. All they did was show how it could be done more conveniently. Now numerous things exist that provide a similar level of convenience. End of story (for drop box). They might limp along for another few years but it won't matter. At this point, who even cares?