Browsers are just a feature, not a product.
Applications are just a feature, not a product.
Operating systems are just a feature, not a product.
Depending upon your POV, just about everything can be dismissed as "just" a feature.
But that doesn't change the fact that some things, like word count or auto-adjusting color temperature, are at the end of the feature-product spectrum, and are better off as "just features".
That doesn't mean someone can't try to sell a dedicated program based on just those things.
But nobody should be surprised if other programs or OSes incorporate the same stuff as merely a feature they offer.
No one is writing stuff for f.lux.