It's the confusion between: It is unlikely that Charles Babbage is going to be able to build his difference engine and even if he does it is so complex and so

It's the confusion between: It is unlikely that Charles Babbage is going to be able to build his difference engine and even if he does it is so complex and so prone to failure that it probably will never be commercially viable. vs. It is unlikely that Charles Babbage is going to be able to build his difference engine, thus proving computers can't work and have no utility.