Indeed, OHM is the wiki world map that anyone can edit. 
@SomeoneElse might have been frustrated about what I said in that thread about copying from OSM to OHM. It’s not that OHM’s Powers That Be don’t want to help OSM mappers; it’s that we want to be a good partner to the OSM community, and a big part of that is respecting OSM’s license. Otherwise, what message does this send to people who would co-opt OSM for commercial gain?
Anyways, there was a similar discussion recently about these historic census boundaries and the relationship to townlands:
As you know, the U.S. community is more cautious about importing census boundaries. But the arguments in favor of the Irish census boundaries are slightly different, that they have legal force and are useful for genealogical research. This makes them quite analogous to survey boundaries, which the U.S. community has a complicated relationship with, especially in New England.
The easy answer is that all these boundaries certainly belong in OHM, but as long as there’s also some attachment to them in OSM, that critical mass undercuts any local interest in building out OHM’s coverage. Without that interest, OHM would be taking, not partnering. Rather than offering to take the Irish community’s hard work, OHM’s offer first of all is to seek a partnership with the community and help them get their feet wet in the project.
Anyone is welcome to use the first-party OHM vector tileset for their projects without restriction (though credit to OHM would be much appreciated). The schema isn’t stable and there are lots of known issues, but the development team is actively working through them. The tileset updates minutely at higher zoom levels and slightly less frequently at lower zoom levels.
An alternative tileset would be cool too, of course. The existing OSMUS tile service is somewhat geared towards the OpenMapTiles schema, which isn’t quite ready for OHM data (no dates), but Planetiler is capable of many things that are challenging with the older Tegola-based stack.