what i mean is every thread on BOA is the same page: 'showthread.php'
the difference is pulled off the database using parameters passed in the url: "p=514280#post514280"

although it is possible to save each page will a litteral file name, to then check every single page that each and every hyperlink follows would be far to impractical to be worth the time coding.

plus the size of the site would be imence if you've got an uncompressed ACSII file stored for each thread compared to one db file. especially when the archive site hosts hundreds of forums.

so in short - it's not impossible to do what you say, but it is far too impractical for any companies to bother programming a free-to-use resource for every single forum for x number of months for every year.