PDF is an unusual format in the sense that it had a rather specific thing it tried to do and then it achieved that goal, so that it could be considered "done", but the product it was most associated with, Acrobat, tried to expand still.
PDF has the semantics of a digital print that is resolution-independent and supports copypaste and search (mostly by mapping glyphs back to text).
In addition to resolution independence being something that's higher-level than strictly "digital print", being able to capture transparency is such a higher-level feature.
From the above perspective, PDF peaked in 1.4 when it got transparency support. Supporting roughly the PDF 1.4 feature set was that allowed the Mac Preview app be good enough for Mac users so that Apple could stop bundling Acrobat Reader with Macs.
After 1.4, PDF has gotten better compression algorithms that don't really change what the format is about. PDF/A and PDF/X fit well the notion of PDF as "digital print".
But Adobe has been trying to leverage Acrobat/PDF to other areas that don't fit the notion of "digital print". These include pre-Macromedia acquisition attempts to make PDFs a more dynamic platform and later inclusion of 3D models in PDFs. Other PDF viewers still work for users most of the time without this stuff, which is a signal of what PDF really is to users ("digital print").
(Filling in paper-like forms, while not true to the notion that PDF is a final-form format sort of make sense from the point of view of digital paper, though.)
PDF has the semantics of a digital print that is resolution-independent and supports copypaste and search (mostly by mapping glyphs back to text).
In addition to resolution independence being something that's higher-level than strictly "digital print", being able to capture transparency is such a higher-level feature.
From the above perspective, PDF peaked in 1.4 when it got transparency support. Supporting roughly the PDF 1.4 feature set was that allowed the Mac Preview app be good enough for Mac users so that Apple could stop bundling Acrobat Reader with Macs.
After 1.4, PDF has gotten better compression algorithms that don't really change what the format is about. PDF/A and PDF/X fit well the notion of PDF as "digital print".
But Adobe has been trying to leverage Acrobat/PDF to other areas that don't fit the notion of "digital print". These include pre-Macromedia acquisition attempts to make PDFs a more dynamic platform and later inclusion of 3D models in PDFs. Other PDF viewers still work for users most of the time without this stuff, which is a signal of what PDF really is to users ("digital print").
(Filling in paper-like forms, while not true to the notion that PDF is a final-form format sort of make sense from the point of view of digital paper, though.)