Any solution that requires receiver/amp/combo and wires is going to be limited where you can deploy it.
Before wireless audio like Sonos, most people have a stereo in one room in the house. Now many people have speakers in almost every room in the house.
I got rid of my Onkyo receiver and JBL studio series to go with Sonos because it is a better listening experience in the real-world. Audio being synced across your house is the real deal.
But I am a little concerned that when I move to the new iDroid Megapixel XXXL 3000 in late 2025, I'll have to replace them all if I want to be able to send audio from my phone to the speakers.
When having the sync across the whole house is the main reason you like the setup, it's even more galling to need to replace them all. I wish (and will be watching to see if they do, before I add any more speakers to their system) they'd come up with an upgrade path.
It'd seem like a smart thing for them to do. Surely they could come up with some kind of bridge gadget you could connect to your network between the old and new for the cost of about one speaker. That'd spare them having people angrily leave their ecosystem because, if you need to do 5 rooms at once anyway, you might as well shop around.
They are no longer. The iPhone makes a great controller. Spotify and Tidal mean we don't need a local file store. Speakers from Bluesound, Amazon, Google and Apple compete at various price points at the low end. If you do want to spend on a local controller, then Roon, a spin-off of ultra-audiophile Meridian, has a better experience than Sonos, and is supported by brands like Meridian, Naim, Nad, Trinnov and $100 hifiberries.
I have Mission speakers in the bedroom. Meridian speakers and a hifiberry in the lounge. A 7.1 system with another hifiberry in the TV room. Bluesounds in the kitchen and dining room. And the bluesounds have battery packs, so I can carry them into the garden if it will ever stop raining. With Roon, they all play the same music in perfect sync. A new "remote" cost me $49 for a 7" Amazon tablet, but I can also use the phone in my pocket, or the iPad upstairs.
So Sonos is competing with Echo Studios, Bluesounds, Apple and Google, at the low end, and it's being beaten by a pure software company who is integrating with audiophile kit at the high end. That software company charges a subscription. It's not relying on hardware sales, just as those sales are getting killed by cheap competitors.
Meanwhile they've got legacy kit. IIRC the original stuff set up its own wifi network that it controlled in a proprietary fashion. Nowadays, competing devices just work on whatever you wifi you got, and I assume Sonos' newer devices do too. That can't be fun to sort out, hence the "two networks" solution. To be competitive, they have to cut the old stuff loose.