I feel it's more that they built Elidibus up to be too good an opponent previously, and they couldn't find a way for the protagonists to convincingly beat him so his ability had to be undermined instead.

(And then took a further jarring shift with Tales From recasting him as an "adoring younger brother" type to the group, which is... what.)

Additionally, his presumed role in Pandæmonium means that he doesn't get to appear in the credits "passing the torch" scene with the others, because they can't officially show him as an ancient and identifiably Elidibus yet.