In the past I would have said: yes because running queries on a spark cluster is not that fast.
But right now, with Databricks SQL I don't immediately see the added value.
A use case could be proprietary login method (SQL Server login f..e.), or more tuning options (table type f.e.).
It can also be that Synapse is cheaper/faster than Databricks SQL for your use case.
So in general I'd say that there is no reason to use Synapse, but it might be possible that for your use case it is a good choice.