Agile Adoption in companies are typically initiated by IT. While at a smaller scale, agile experiments without both Business & IT leadership alignment might demonstrate some success, organization level agile adoption simply cannot succeed unless business and IT leadership are both committed to Agile Adoption.
Agile teams require persistent or dedicated Business & IT roles to be embedded at all levels within the delivery organization. Agile brings a paradigm shift to how Business & IT people collaborate within same teams on a regular basis. Lack of commitment to fulfill those roles results in inadequate formation of teams, gaps in planning and delivery, not to mention Agile being blamed to be ineffective when Business & IT collective commitment was not there for Agile to be successful.