The answer to this is easy: copy imessage. If Apple had even a little bit of common sense they'd support imessage on windows and android and just charge a small fee of some sort to make money off of it. They're blackberry right now, they could own the market if they were willing to eat their own market share.
As for google: I have no idea what is up with the stupidity. What people want is simple: an app that works on the PC and the phone, that can do messaging that falls back to SMS if the other-end isn't capable of "data" based communications, and ideally has encryption as an option and video chat as an option. Hangouts was like 90% of the way there, and then for some reason they went insert offensive analogy here and decided to release allo and duo with half the functionality. And oh by the way, after the release of those two apps, Hangouts started acting goofy for a month (which I struggle to believe is coincidence as much as I hate conspiracy BS).
Apple wanted to open it up, supposedly, but I read somewhere that they were apparently blocked by lawsuits with VirnetX (an apparent NPE/patent-troll), ongoing since 2010.
You may be thinking of FaceTime. Apple was going to open that, but a successful lawsuit by a patent troll (I think it was VirnetX) put a stop to that, because Apple had to change FaceTime to proxy through their own servers, which meant that opening it up wouldn't do any good.
That said, VirnetX has also sued Apple about iMessage, so it's possible there's something to what you've said (but I've never heard it said before that Apple was going to open up iMessage).
Steve Jobs famously believed in cannibalizing their own sales. (Or, to be less charitably, he believed in that when it was convenient to believe that).
Whether the culture has carried over, who knows.
Even as an iPhone user, I never would have thought iMessage was even in the top 5 or 10 reasons to keep using the platform. But I'm old, don't text all that much, and have unlimited SMS anyway.
I imagine all the cool kids these days are using alternative data-based services anyway. Snapchat, the like. For us old folks, WhatsApp, GroupMe, etc.
It's not necessarily the experience on the phone that is lacking in other SMS based apps on competing platforms -- I see it as the ability to leverage being able to message anyone from most platforms be it conputer, iPad, or phone and have it all in sync. That to me is the massive draw to it.
I kind of wonder if there isn't more to this. Perhaps it's why Continuity [1] never fulfilled its full vision of moving seamlessly between iOS and macOS. Lack of support for third party apps, especially messaging apps, felt intentional.
In Apple's case, I don't think a lack of common sense is the problem. With the iPhone making the bulk to Apple's revenue, this is a textbook example of a "strategy tax" [0], and the thing about strategy taxes is they're really hard to overcome even when you can see the issue staring you dead in the face. It takes very uncommon leadership to hobble your cash cow.
After reading that article, it honestly sounds like the author is arguing against the entire concept of strategy, and would probably love Google's "I realize we already have two of those we put no effort into maintaining, but let's compete with ourselves by launching a third and telling everyone it's the future" anti-strategy strategy. Hell: what I want from Google is to see a strategy, as all I am seeing is complete and total chaos. What this article calls "strategy tax" would be better called "bad strategy", and I don't really see the alternative suggestions as better, as there are assuradely solutions (such as making your web browser a component and sharing a layout engine with the word processor, allowing the browser to edit and save simple documents in the format of the word processor, which is then essentially a paid upgrade to the basic editor) that make more sense than "let's sacrifice our high ground on what sounds like a bet".
At least some of the stupidity must be due to how many good ex-Google engineers I've met - and how many lame duck engineers who have positioned their resumes and lives just to be hired there for status purposes.
As for google: I have no idea what is up with the stupidity. What people want is simple: an app that works on the PC and the phone, that can do messaging that falls back to SMS if the other-end isn't capable of "data" based communications, and ideally has encryption as an option and video chat as an option. Hangouts was like 90% of the way there, and then for some reason they went insert offensive analogy here and decided to release allo and duo with half the functionality. And oh by the way, after the release of those two apps, Hangouts started acting goofy for a month (which I struggle to believe is coincidence as much as I hate conspiracy BS).