People who were developing "office" programs in the early 1990s were thinking about the problem of serializing arbitrary object graphs into documents to support technologies like

https://en.wikipedia.org/wiki/Object_Linking_and_Embedding

where you could embed an Excel spreadsheet inside a Word document or actually embedded any of a large range of COM objects into a Word document which on one hand is a really appealing vision but on the other hand means you have to have and be able to run all the binaries for all the objects that live in a document which ties the whole thing to Windows.

PDF is a different sort of document format which privileges viewing over editing but it is also really about serializing an object graph when it comes down to it and then having various sorts of filters and transformations and a range of objects defined in the spec as opposed to open ended access to an object library.

This kind of system has a lot of overlap with the serdes problem you get with RPC frameworks that used to be under the files "Sun RPC sucks", "DCOM Sucks", "CORBA Sucks" and "WS-* Sucks" Those things are mostly forgotten these days because well... they sucked, and now the usual complaint is "protobuf sucks" but you rarely hear "JSON sucks" because it gave up on graphs for trees, if you don't have a type system people can't say the type system sucks, and the only thing that really sucks about it is that people won't just use ISO 8601 dates but you can always rise above that by just using ISO 8601 dates without asking for permission. But we all agree YAML sucks.

That points to any flexible document format sucking but also sucks because it has lots of poorly specified and obscure features that amount to "format this the same way Word 95 formatted it if you used a certain obscure option".

From a glass is half empty perspective it sucks because it's close to impossible to make a Microsoft Office replacement that renders 100% of documents 100% correctly.

From a glass is half empty perspective it rules because if you want to make a Python script that writes an Excel script with formulas it is easy. If you want to extract the images out of a Word document it is easy because a Word document is just a ZIP file. If you want to do anything with an OOXML document short of writing an Office replacement it's actually a pretty good situation.

> but you rarely hear "JSON sucks" because it gave up on graphs for trees

Except it also spawned a thousand custom formats that include $ref support of some type, so we are right back to having graphs. :-D