In software, you need to track versions because you keep everything in multiple files, and you're making changes to multiple files, and you can have regressions with each new version.
In a negotiated legal document, you have just the one authoritative version: the offer you've sent to the other party (or the counter-offer they've sent back to you). For lawyers, this takes the form of edits to the document as highlighted by the Track Changes feature. (Prior versions are basically irrelevant except for historical interest.) And even then, the document going back and forth isn't even the executed (aka "production") document, it's just the development version. Once the document is executed, the development versions get deleted because the executed document is the only truth legally and so prior versions absolutely do not matter.