Yeah, because Baby Tiragon's a bigger problem than Sea Stealth Attack. ;p Everything's relative. There's powerful Xyz monsters and completely worthless ones. Never got why people have such hatred for entire mechanics they more than likely know nothing about.
Not to mention, Pendulum won't be busted in DL if this game uses MR4 ruling like in TCG/OCG.
Under MR4, Pendulum monsters, when used as Scales, are placed in the same slot as S/T zone, meaning you only have 1 S/T slot to work with since the remaining 2 are clogged by the Scales.
And there's actually not that many busted Synchro or Xyz. Konami can just not implement them into the game.