My system has been rock solid for 10 years.  7 zones, 14 devices.  I suggest you post actual details of your problems so that your local issues can be resolved. 

13 years, 11 zones, 20 devices (currently, as a handful are in storage). Apart from the occasional explainable glitch it just worked. Glitches were almost always due to network gremlins, as I’m pretty sure would be the case for the OP as well.

“Sonos always blame the network!!!” someone is sure to holler from the sidelines. Well, I’m sorry, but without a sound local network a multi-room networked audio system simply can’t function successfully.

Could it be the case that devices like Echo, that are not multi room networked, can cope better with a less sound local network?

Even while my 5 zone Sonos system is very stable now - and after being on a no upgrades S1 environment for over a year, seemingly even more so - from the start in 2017, my Echo devices have been even more trouble free. 

As we never tire of reminding folk, any device which simply connects out to the internet asks a lot less of the local network than a system which depends heavily on device-to-device communications.

Right; so that would suggest that the issues seen in Sonos are an occasional price to pay for those that must have the feature of group play. 

As I see it the networked play feature was needed for more than one user/room to access a single music resource in the home on a NAS or similar, before the advent of streaming services. The latter means that anyone in the home can access these and play music on a system that is not device to device. 

The other reason for device to device is where in sync play is needed in more than one room. The question then is how many that buy Sonos/similar really need this feature and its associated overhead.

Those that need neither feature are better served on the uptime angle by devices that don’t do device to device, and as the subset of the user base that use a NAS is shrinking per Sonos own admissions, so may that be for in sync multi room with new Sonos buyers today - for instance for someone that buys a Roam. But such a buyer is still burdened with the overhead of device to device architecture that is quoted above, with the associated consequences.

Controller-to-player is device-to-device. Player-to-NAS is device-to-device. 

Which means even a single Sonos unit set up playing a streaming service is device to device? Whereas music play using Spotify Connect on a phone to transfer the stream to an Echo device isn’t? 

When does this device to device thing that was designed for the start up Sonos USP become a handicap given the profile of the user base now? Or will networks get improved in time to allow for better Sonos uptimes, still using the device to device architecture?

The Sonos controller to the player is local device-to-device. The player connects out to the internet, device-to-server, to fetch the stream.

Spotify Connect uses a cloud-based bridge to pass control commands to the player, which then connects out to the internet to fetch the stream.

That isn’t Sonos’ USP; it’s UPnP. 

Increasingly local networks are being broken by the introduction of additional components -- such as mesh routers -- which either due to user misunderstanding or faulty firmware interfere with the basic operating principles of UPnP, e.g. a single, flat, broadcast domain.

Whether Sonos will eventually go over to a fully cloud-based control architecture I haven’t the remotest idea. Even if they did, the stream would still need to be passed around locally between group members.

To the first: I meant that to be the one with its USP, Sonos had to use the latter. And now they are still with it, while local networks come in the way of it working properly, as you describe.

No idea of how they will approach this problem - or even if it is a big problem for them, and if it is, if they see it as such - but with cloud based control any issues with the stream having to still be passed around locally would then only impact those using the group play features. Today it also impacts those that have no interest in group play.

For someone who has semi-abandoned Sonos -- at least in terms of future software and hardware developments -- you do seem unnecessarily troubled by what you perceive to be its architectural weaknesses.

Not troubled at all. But such speculation tests and sometime increases my understanding of tech, which is always useful.

It also helps make more robust recommendations to users here and elsewhere.

Also, since my understanding of Sonos products on S2 like Move or Roam is no longer hands on, there is much less to do with respect to the many other posts on these products that fill the forum now. So I have more time on my hands:-).