WWE's fear of losing talent to AEW, New Japan, ROH, Impact or any other promotion in this saturated wrestling climate means they're approaching WCW levels of roster gluttony. It's also presumably why there are so many stars currently sitting around twiddling their thumbs and doing precisely bugger all for their salaries.
Hey, nobody's judging, but it is a bit weird to have skilled players stagnating on the bench for so long.
Don't read too much into Triple H's recent comments questioning whether or not this is actually a wrestling war. It very much is, and WWE didn't get to the top by underestimating potential competition. They know full well that AEW has solid financial backing, has already stolen away big names like Chris Jericho and Jon Moxley, and could be a long-term threat when they land on TNT.
Internally then, it's anyone's guess what those wrestlers struggling to get on TV think. Others have become so disillusioned by WWE life that they'd rather chill out for a while, pursue side projects or assess their options during the second half of 2019.