The NWA basically allows the champion to do what we saw at ALL In. It lets the champion travel to other promotions and defend the belt on shows. Back before the NWA shot itself in the ass in the early 2010's and led to them selling to Corgan , the champion would travel and defend the belt. It was defended on Ring of Honor and other promotions cards.
The NWA had some bad bumps along the way as we saw from the WCW and TNA situations. But really as I posted what led to the sale was the Adam Pearce/Colt Cobana situation. Pearce was considered a strong champion who had carried the belt 5 times from 2007 to 2012 and had defended it pretty solid. Anyhow the blow up came when Cobana/Pearce had a best of 7 series (the 7 levels of Hate series) where both men exchanged the belt in that span and with Pearce as champion the final match was to take place in Australia.
The NWA refused to sanction the match which angered both guys who pretty much had Cobana win the final match and refuse the title. Pearce also refused to take the title and left it. This kinda ticked things down to where it was sold a few years later to Corgan.