Sadly, it's not overexaggerated. Honestly if he either had 1) disjointed aerials/tilts, 2) more range in his grab/true combos that start from a grab, 3) a spammable projectile, or 4) better aerial mobility, he'd be leaps and bounds better. Definitely being held back a lot because of his flaws.
It's very sad, but Kirby really is a terrible character. IMO his strengths don't do enough to win against his many flaws.
Key differences between King Dedede and Kirby are how fast they fall and how far their respective aerials reach. DDD can just shorthop an aerial and land pretty fast, not to mention that he even has disjointed aerials (uair, fair, dair), while Kirby jumps slow + falls slow + moves slow in the air + has zero disjointed aerials (with the exception of his VERY punishable specials). It just so happens that this is countered by the fact that Kirby is pretty light so he's not easily combo'd, unlike DDD.
He has awesome speed, disjoints in tons of attacks both in the ground and in the air, a spammable projectile that can gimp offstage, and can kill pretty early with a few safe moves. Not to mention his super fast ground speed, which allows him to punish players that do short-hop aerials/rolls/whatever.