Re: "Linux is quietly running on a myriad of embedded devices"
"And being FOSS doesn't automagically keep them up to date."
Being commercial doesn't automagically do that either. Apple has given up on my iPad Mini. Microsoft has given up on XP. Many Android vendors gave up on your device before you even purchased it.
"Really? In which ways?"
Perhaps more reliable devices due to a reasonably stable base to begin with? Or maybe less expensive devices because nobody had to factor "write an entire operating system" into anything. Not to mention, with some devices you can throw away the manufacturer stuff and put your own in its place. Such as OpenWRT, for example.
"Letting Facebook, Google and Amazon amass an enormous power?"
As much as I'm all for bashing those three, I think you'll find their use of open source is more a "when it is useful to them" rather than a significant factor in what made them the entities that they are now.
Google, for example, started out life as a faster ad-free alternative to AltaVista and the like. This was important in a dial-up world. As line speeds increased, they started adding in some "sponsored" things, and, well, it grew into an empire.
Facebook? Built on the backs of people willing to blather every thought that passed through their vacuous minds. The lure of analysing data points for targeted advertising wasn't far away.
And Amazon, originally the world's biggest bookstore, now sells pretty much anything (and far too much of that is counterfeit crap). That empire was built upon somebody smart enough to figure out how to streamline online selling to the point of making it as addictive as gambling, and organising a logistics network to ensure it all actually worked.
"do you really believe that giving something away for free could end in a different way?"
I'm far too cynical. The question isn't so much whether or not it could have ended in a different way, but more what needs to be done to alter the current trajectory.
Once upon a time the concept of open source in any sort of serious context was practically unknown. Enough people had the same general vision, even if there were disagreements (BSD vs GPL, for example), that open source became a reality. And rather than being a useful program that had its source in the archive in case you wanted to fiddle with, it instead became entire operating systems. Ones that are arguably more solid and hardened than the typical commercial offerings.
"it's just some kind of religious belief sustaining FOSS"
You might almost have a point if you replaced FOSS with GPL, but it's not necessarily a valid point with FOSS, as that spans the gamut from the rather restrictive GPL to the "I don't give a shit" three line BSD licences, and many such as the person above, who make their contributions in order to scratch their own personal itch. To quash their favourite pet bug. And, look, you can actually do that with an open source project. Spot a bug, look to work out how and why, develop a fix, submit a patch. Let's see my long list of iOS/Android/Windows bugs get fixed in a similar manner. Oh, wait, nobody gets to see that so no third party fixing is available. You just gotta rely upon the in-house developers fixing things, but that's a pretty big hope as in my experience they're too busy fucking with the UI for no good reason to spend time looking for annoying bugs to fix.
There is no easy answer, sadly. But calling FOSS a religion? That's not an answer at all.