"Perhaps they've decided that this is a small and declining market."
For consumers (and facebook is a consumer company) it's all about who owns mobile (and can also compete with facebook). They want desktop to just be enough of a feature to be more appealing than other platforms, but not enough that it detracts from mobile.
For consumers (and facebook is a consumer company) it's all about who owns mobile (and can also compete with facebook). They want desktop to just be enough of a feature to be more appealing than other platforms, but not enough that it detracts from mobile.