The Americans with Disabilities Act, which can be used to sue developers of inaccessible websites, has made it clear that in some cases serving the majority can be a bad thing.
Less severely, there's an awful lot of long tail business productivity served by obscure software features that is very difficult to satisfy with modern hyper-engagement-optimized tools.
I'm pretty sure there are false dichotomies going on here.
Software products may be developed for a mass audience or they may be developed for a narrow niche.
In either case, making the product accessible to people with disabilities is something developers should try to do.
And in every case, having data on user behaviour, software performance, bugs, crashes, etc, will enable the developer to do a better job of catering to their users' needs.
Have I missed something about how these objectives must be mutually exclusive?