Well, some think it was to show off their writing. Personally, I think it was feature of a more oral age, because run-on sentences and otherwise odd gramatical structure are way more tolerable when read out loud.
And if you're dictating to a scribe, or writing something which is intended to be a long spoken exposition of some subject (like a sermon or a lecture), then it's less likely that you'll pick on how odd they seem when read. More even, if the majority of readers does read things out loud (which might have been the case) then it won't seem as strange to them too.
And if you're dictating to a scribe, or writing something which is intended to be a long spoken exposition of some subject (like a sermon or a lecture), then it's less likely that you'll pick on how odd they seem when read. More even, if the majority of readers does read things out loud (which might have been the case) then it won't seem as strange to them too.