Online tables pose an accessibility problem because the visual layout that makes them so easy to read is pretty incomprehensible to software screen readers.
People born blind still learn tabular structures through tactile tools (braille tables, raised-line grids), so the mental model that allows one to navigate a table is presumably not the main challenge to presenting tabular data online.
This widget is designed to allow the user to break moderate-sized tables into logical chunks that can be navigated by ear.