Yes, but that means any EU's who have got into Ireland from the continent legitimately with just their ID card have entered the UK with zero processing. Not that it's an issue, but when you consider all UK ports of entry (other than those from the Republic) will be putting severe measures in place to keep out EU "undesirables" such as full passport, entry form, profiling etc anyone wanting to bypass all that can simply fly to Dublin, enter the CTA with just their ID card and get that very same ferry. Unchecked and over here.
You'd have thought a politician would have worked that out by now, and my MP certainly does as I told him that very fact in 2016.
What we need is a few youtubers doing it with their ID card, seems to be the only way to get things done!!