They are, and both BIS and Chandos have long released their albums as Hybrid SACDs, but big boxes collecting together the complete output of particular artists are more common than ever, and these are mostly from Warner and Universal, and on CD only (they haven't really taken SACD to their hearts). The sets aren't generally made available as downloads either, though it's quite often possible to piece most of a set together with individual releases. Then there's some single album releases that never see any kind of physical release. Being into classical and/or jazz music these days definitely needs a format-agnostic mindset.