MSDTC – Give it a dedicated group or use Cluster Group? – Database Forum

The only reason to give it its own group is performance.

If you have a high load/use for MSDTC, you should configure it in its own
group, however this will impact available drive letters, as the dedicated
group needs a disk (and IP and net-name). If you decide to give MSDTC its
own group, you must carefully design the rest of your cluster in regards to
the available drive letters.

Most applications do not have a high load on MSDTC, and therefore there is
not need for a seperate group. It is very common to place the MSDTC resource
in the Cluster Group, using the Quorum disk

Microsoft SQL Server Support Blog : MSDTC and SQL Server on a cluster
Should MSDTC be in its own resource group?
To help ensure availability between multiple clustered applications, Microsoft highly recommends that the MS DTC have its own resource group and resources. If MS DTC cannot be configured to have its own resource group, the recommended alternate choice is to use the Cluster group and Quorum drive.

How to configure Microsoft Distributed Transaction Coordinator on a Windows Server 2003 cluster
When creating the MS DTC, moving the resource group into a group other than SQL Server or Exchange Server group is highly recommended. Creating the MS DTC resource in its own resource group and assigning it to a separate cluster group keeps the resource highly available.