Because "web only" is what Google is about. It works pretty well for them honestly. Android phones and Chromebooks are selling pretty darned well.
For the most part that's what people seem to want these days. Even for the "keyboard, mouse and screen" form factor you'll likely see a shift to those type of devices. As said Chromebooks are already selling very well, but they're also introducing Chrome "desktops" - basically a chromebook that connects to external peripherals (ie, the Acer Chromebox CXI).
In less than 10 years a full computer running local apps won't be commonplace for "regular people" anymore. You'll likely see them relegated to use by content creators, programmers, and hobbyists like us.
It's kind of odd that Linux might finally succeed as the dominate desktop OS eventually - because eventually a desktop OS might not really be a viable retail product anymore.