Try writing a 500 page document, complete with TOCs, indices, tables, lists, footnotes, endnotes, references, etc. in something like Google Docs sometime.
It has certainly been the case even in the past year or two that the happless art history major with a senior thesis project due soon, but whose machine doesn't have the resources to handle the document or have to deal with unexpected changes in formatting because they switched which printer they'll be printing to!
obvious they should be using latex over word :p, but the point is that theres a tradeoff on where the abstractions are and who has to deal with them.
Seriously though, anyone on HN who regularly writes large documents and cares about their formatting etc being nice, should have a go at latex! :)
Handling very large text files is something the old unix tools did well (I can load a 500Mb log file (don't ask :/) in vi no problems), but most modern applications still struggle
Why, in this day and, would anyone want a 500 page printed document? Something that would need updating as soon as it's printed?
The only reason I use 500+ page things is to read them from my couch, something the iPad (and the Kindle, the Sony and the Nook) can do very, very well. In fact, I carry about 100 books in electronic form with me on my iPod (which could be described as an "iPad Nano")
And any reader can do even better if it's not a monolithic 500+ page monster, but a neatly organized and searchable website.