The bar/line chart is a categorical chart. The space of the horizontal axis is divided into as many parts as there are distinct categories, i.e. values of the "category" visual-role/dimension. Both bars and lines/dots are then placed horizontally centered in the corresponding categorical area/band.
How exactly would you want lines to extend?
- Should all points/lines be placed at the left position of each categorical band, thus leaving the last band without data (or would need to extend to the end, in the last band)?
- Should these be aligned to the left (in which case, for the first band, the line would need to be extended to the beginning?
- Should dots/lines continue centered in the categorical bands and the first and last bands extend the line to the beginning and end, respectively?
In a time-series/continuous-category Line chart, dots and lines do show up like you describe.
Btw, do you know https://community.hitachivantara.com/s/article/ccc-community-chart-components-faq?