Except Twitter
used to offer "extremely deep API support...allow[ing] folks to build applications that leverage [their] platform in unique ways." And then they couldn't make any money that way.
I'm really not sure you have a good example of a loss of an open ecosystem here. NewsGator's plans were to pretty much create the equivalent of the (unofficial) Google Reader API, which, while not replacing RSS (the actual open format), does notably reduce its role. Moreover, for those who apparently don't remember, NewsGator actually did release their API. The API and their free reader software is what they shut down in 2009.
You can blame that on Google, who did indeed retain the lion's share of users, or you could blame the self defeating business plan of providing a completely open API for free even while it costs money to run. A NewsGator API is not a loss in terms of a loss of an open ecosystem (and Bloglines was definitely not a loss).
If you want open, you need a real federated protocol. Like RSS.
Meanwhile, this article says "RSS industry" in the headline, but it's about nothing like that. The author says it himself: "No, Google Reader’s real competition back in its early days was not client software but services that aggregated RSS feeds and synchronized them across multiple devices."
You can't embrace, extend, and extinguish services that have no standard format. RSS is doing just fine. What was lost here was a UI and a service, which leaves us with user migration pain and a loss of continuity of history (due to indefinite feed history).
We'll likely always need some services. Yes, I can run a feed aggregator on my home machine, but it's kind of a waste, and not everyone has stable IP addresses they can use to sync across devices. Instead of giving up on services, what we need to learn from this is to make sure the next services we allow ourselves to depend on don't have control of our history, both individually and collectively. Notably Facebook, Twitter, and G+ don't fit this bill, or fit it only partially.
(Unfortunately, our collective history on those services is complicated by visibility/access by person controls, so maybe there isn't a perfect solution. I know I can use takeout to download my posts on G+, for instance, but what about my comments on others' posts, and what about those posts themselves as context for my comments? And what about the major news of the day, even if I didn't comment?
Sigh...we need a modern usenet...)