Knowing that makes a lot of sense. Sometimes his prose can read like a sentence that was started but he’s too much effort in to give up on. It probably helps his writing to do it by hand - you can’t edit quickly on the fly with paper (unless you’re cutting stuff out). I could see this as being part of his process - just write and let the editing happen later.
Whatever the process it is, long as his books may be, it works.
This actually explains why I've never been able to get into his writing despite rave reviews and countless recommendations by people I know. Something about his writing always just felt tedious to me. Im an avid reader btw.
His earlier stuff was much better. If you tried Snow Crash or Diamond Age and didn't like them, he's not the author for you, but if you tried his more recent crap like Anathem I would strongly advise you not to judge him based on it.
Give his earlier works a try and you may find he used to be able to write well (ie. he used to actually edit his work), before he stopped caring and just wrote 1000 pages of unfiltered garbage.