But Mozilla are still pouring mental and financial resources into Pocket, including the servers to host it and power its recommendations. So just ignoring it still leaves a deleterious effect on Firefox overall.

They make money off of Pocket. Companies can pay to have their articles be in the pool of recommendable articles.

And it's especially also a different source of income than search engines. They try to differentiate here, in case for example Google's monopoly becomes even more extreme and they push the price down.

And exactly in this vein, a big motivation for Pocket is competing with search engines in general. It tries to be another channel through which users can discover new content, so that Google can't determine everything you believe in without any hindrance.