Data residency
The most common reason, and it is usually decisive rather than a preference. If your obligations require telemetry to remain inside Saudi Arabia, the question is not which tool has better dashboards: it is which tools can run where you are permitted to put the data. That normally means a self-hosted stack on in-Kingdom infrastructure.
Settle this before the evaluation, not after. Logs in particular routinely contain more sensitive material than teams expect, and discovering that once agents are deployed is an expensive way to learn it.