Be able to get the font metrics.
When fonts aren’t installed the user sees a substitution(?). If it’s possible to get the font metrics suitable shaped fonts could be suggested.
This would also help if you are exporting the text to another format. You can get the correct caps height and possibly path data and other values to position the text accurately across platforms.
To correctly position text we need to get the caps height and be able to align to the caps height (in the browser and other devices) at least for the first line of text.