Sam Tobin-Hochstadt writes:
The new standard is gratuitously incompatible with the current standard for Scheme. It is the job of standards committees to produce compatibility and interoperability, instead this committee chose the opposite route. For example, despite isomorphic features, the module system is incompatible with the current standard.
The WG decided by unanimous consent to take no action on this ticket.
R6RS in turn was incompatible with existing practice as expressed in SRFIs and implementations. Many of the incompatibilities in the draft exist for compatibility with this pre-existing practice.