If there's no traceability, there's no way to ban miners who perform block withholding attacks.  nostr:nprofile1qqsvvk9qy7qx2gzed6wazxtureunuxljam66za6yr3p02zc0qhz57jqpzemhxue69uhk2er9dchxummnw3ezumrpdejz7qgcwaehxw309ahx7um5wghxvmt59emkj73wvf5h5tcpz4mhxue69uhhyetvv9ujuerpd46hxtnfduhs0dsl3l has recently written about this problem and potential solutions (e.g. oblivious shares, which alas requires an invasive hard fork).