But many use it to read PDFs and to add annotations to them, which aren’t particularly demanding requirements. Preview isn’t, of course, a ‘serious’ PDF editor. One obvious result is that Preview acquired its own bugs in handling PDFs, and hasn’t really recovered yet. Among the apps which had to do this was Apple’s own Preview. The new version broke a lot of existing code, and developers were forced to work around those bugs.
A few years ago, Apple decided to completely rewrite its support for PDFs in PDFKit and Quartz2D.
