So even if SQL is installed as non clustered, DTC can still become involved somehow
Yep.
If that's the case, why when dealing with Clustered instances of SQL Server do we have to explicitly create a DTC component in the Cluster?
My understanding is that the Windows cluster relies on it. DTC is not a SQL Server-specific piece of software. It is a stand-alone Windows service that SQL Server sometimes leverages. SQL Server clusters sit on top of Windows clusters, and its the Windows cluster that requires the DTC to be configured.
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