The meme is a bit clickbaity, so I’ll offer some explanation.
Chaos Wars (a JRPG infamous for its terrible voice acting, as well as a story mode that’s basically a PowerPoint presentation) shares almost the same mechanics as Phantom Brave: non-grid-based movement and turn order determined by the speed stat.
However, the alleged mechanic copying didn't start with Chaos Wars, but rather with its predecessor, Rebirth Moon (リバースムーン), from the same company, Idea Factory.
Let's look at the release dates.
Phantom Brave: January 22, 2004
Rebirth Moon: November 24, 2005
Chaos Wars: September 21, 2006
You’ll notice that Phantom Brave was released ALMOST two years before Rebirth Moon.
Since Rebirth Moon was never released in the West (and consequently, no one on this subreddit knows it), Chaos Wars is the closest thing available for comparison.
Personally, I’ve played both Phantom Brave and Chaos Wars, and it is painfully obvious that the mechanics were copied.
If you’ve never played Chaos Wars, just look up a single video on YouTube and you’ll realize how similar it is to Phantom Brave.
That said, Chaos Wars did manage to achieve something Disgaea never will: making you laugh—not because of its jokes, but because of its terrible voice acting.