I agree with the recent posts.
Being a member of an alliance and having codeshares is probably a sufficient incentive to attract some customers, being a member of FB adds little. In part, that is because the few FB miles (often zero) earned on a "cheap" airline like UX provides little motivation, while the fee charged by FB to UX must be large.
The move by SN, which is part of the LH group, is quite interesting. You earn three loops per euro spent on any SN flight in Europe and can spend on SN European flight. That can be an attractive loyalty program.

And it is true that a FFP is a financial product and many FFPs are/were profit machines. I still remember the good time when BMI had DC, a money-making FFP on star alliance. Many members never flew on BMI but enjoyed the earn/burn ratio provided by DC. But I doubt that this type of FFP would fly today.