My father used to turn shredded newspaper into his garden at the end of the season to help lighten the hardpan. He was able to acquire the paper already shredded, which made it convenient. I tried newspaper as a layer in a "lasagna" soil-building project and found that it remained intact, almost unchanged, for years while the other layers slowly degraded. Newspaper was not good there. However, now when I am building a new garden on top of land that is weedy or grassy, I start with a thick layer of newspaper put right onto the ground as a weed barrier. It works beautifully. I also use it as a barrier when putting in a pathway that will be "paved" with wood chips or gravel.
I too have found newspaper an excellent way to prep an old lawn area for its new purpose as a garden. I laid down a two-to-three sheet layer, topped with other mulch/compost to hold it down last fall, then proceeded to build raised beds over it. No bothersome grass in the places the paper wasn't disturbed. It also woeks well under garden cloth topped with woodchips as a path.