Splitting rent among roommates is not specific to San Francisco, it's common to cities with expensive housing. LA, Miami, NYC, San Diego, etc. all have high proportions of adults living with roommates (https://porch.com/advice/cities-whose-residents-likely-live-...).
Having roommates certainly helps save money, but it remains true that you and your roommates are paying for some of the most expensive housing in the country.
I don't this contradicts the "gone the way of the DSLR market" claim. Sonos and similar systems are simply good enough for most people.
Whether it's TVs, cameras, surround sound systems, we reached a point of diminishing returns by cramming in more pixels or speakers. At that point, you're competing on factors like convenience. There will still be markets for 7.1+ surround sound or DSLR cameras, but they're smaller now.
It's wild. Single family houses are being listed at $2M-$3M and going for $1M over asking. And the houses would often be considered fairly modest anywhere else in the country.
I imagine a lot of buyers can afford this by selling their existing homes. Or perhaps they socked away a huge nest egg during after an IPO or over the duration of the stock market run up.
But new homebuyers would need to earn about $750k+/year for the foreseeable future for this to make financial sense. That could be a risky wager over the next few years.
Having roommates certainly helps save money, but it remains true that you and your roommates are paying for some of the most expensive housing in the country.