These are workshops paper.
ACM workshops were always like that.
The other thing to look at is the affiliations. All these people work for https://www.epcc.ed.ac.uk/ i.e. they are working for a HPC facility attached to a university.
I see, that's a bit of a relief. Thanks for the clarification. Though I still think it should go to Tom's Hw or ServeTheHome instead of arxiv :)