Your wiki citation talks about it in the botched transition from swing wings to a fixed delta wings. The swing wings were unreliable, and caused quite a bit mo

Your wiki citation talks about it in the botched transition from swing wings to a fixed delta wings. The swing wings were unreliable, and caused quite a bit more chatter in a larger design like an airliner compared to designs like the F-14 (which already aren't really known for being a smooth ride). Converting the design to be a fixed delta wing aircraft had them using crazy ideas like using more or less solid titanium in the air frame, which was never going to be financially viable in the airliner space. You can see some of this today in B-1 lancers, which are very much known for being rough rides, and are pretty close to a half billion dollars a piece compared to <$100M for a B-52 which is significantly closer to airliners wrt design philosophy and cost, and reliability (the B-52 has something like an ~80% ready rate, compared to the B-1's ~50% ready rate).