FScheme still active in Dynamo?

Is FScheme still actively used in the Dynamo codebase? There was a flurry of public FScheme activity in 2013, with associated documentation:

However, searching “FScheme” in the github repository now only turns up files in the src/Legacy directory or tests that have been commented out.

Was FScheme retired from the project? If so, what was its death knell?

Thanks in advance!