Xiba whiffs worse. Anyways its based on the developers not noticing minor holes in their game. Also consider how hard Algol is to design than a basic mundane character like mitsu. Algol would logically have more whiff issues than Mitsu if the characters had the same development time.
Worse than Algol or worse than Xiba? No one has worse whiffing issues than Xiba. Algol and Siegfried are roughly the same, plus some of Siegfried's whiffing issues were put in purposely.
People exaggerate Sieg's whiffing issues, but they're still pretty bad. He can't always get a 3B punish after sidestepping a move that advances forwards (e.g. Alpha 33B, Omega DNS B, etc) because of the tiny hitbox on 3B not dealing with the alignment. He has other hitbox inconsistencies on minor stuff like b4, 66A (who uses this?), 22BB and 2A+B, but it sucks when his go-to whiff punisher becomes unreliable.