@aanchal-sikka That's actually a pretty relevant and good question. I have worked in organisations which stick to AMS over Cloud and also places where they finally 'submitted' to power of cloud services over managed services.
--The AMS was relevant in case where we had integrations with multiple applications which were tightly coupled with certain AEM forms cabailities and the overhead of testing and upgrading was massive, we often ended up in issues like failure in rendering application or data sources not being able to correctly fetch previously filled forms data with new version but still work with older version.
--In another case, certain applications are critical enough (not just from data and privacy perspective) that the upgrade may require longer testing and UAT phase, at times offering better stability to stick to one version longer than to upgrade every quarter.
In certain case, there were custom builts and hotfixes shared by Adobe which made our AEM servers somewhat unique and not easy to simply upgrade, but ofcourse, Adobe emphasises on the idea of maintaining consistent version/updates and being able to leverage new features that arrive with each version.