Cloud based SIEM like Sentinel is the answer to the problems which are faced by mainstream SIEM tools with:
1. Efficient Automation by logic apps and playbooks.
2.Co-relation powered by Machine Learning Algorithms like Fusion.
3.Scalable with inbuilt Data Connectors and ability to design SaaS solution is always scalable.
4.Focused in noise reduction and focusing or reaching and remediation to those which can result in increase/breach of attack surface.
5.Built In the cloud .
6.Scope grows everyday hence integration of threat intel to handle them.