Before the schedule was announced.. did the organizers get the speakers they wanted or did some decline?
Before that.. when CfP responses were rated, did the submitters provide relevant supporting material like a resume of previous speaking appearances (to demonstrate speaking skill) and blog posts, articles, etc (to demonstrate expertise in the topic).
Before that.. did the submitters have writing and speaking skills that made them comfortable to submit?
Before that.. was the CfP well-publicized to relevant groups, companies, etc?
Before that.. was the CfP entirely open? Was it invite only? Was it a blend of the two with only some of the slots open to the CfP?
Before that.. did the person believe they had the skills and expertise to submit?
Before that.. did the person actually have the skills and expertise to submit?
Before that.. did the person have a job or interests to give them the opportunity to learn those skills?
Before that.. did they get encouragement and support along the way?
Before that.. did they receive the education to get the job or choose those interests?
Before that.. did they believe they could learn and work in the industry?
Before that.. did the person have the aptitude for those skills?
If the number at the beginning of this process is small and every one of those steps chips away at the entire group - let alone those with particular genders, ethnicities, etc - of course the output is going to be low.