They added 10 virtual servers in an attempt to expand the capacity of Orcrist. The internal name for those virtual machines is something like "Orcrist Server 81", "Orcrist Server 82", etc through server 90.
When you type /loc in game, the exact server you are on is revealed. People were asked to provide information when they experienced lag, and they found out that by adding these 10 extra servers they actually hit a certain capacity limit, as a lot of data still flows through one master server. The newly added servers caused more problems than they solved, so they were removed. These servers, 81 through 90, became known as the 8x servers.
Based on what Severlin has said on Discord, they have found what their upper limit is for the server architecture, and it appears to be able to host around 2000 people before things start getting laggy. That is still WAY more than any 32-bit server is able to handle, but there is a certain limit.
That is why they likely, and ultimately chose to add a third server. This third server may actually still exist on largely the SAME hardware present, as the upper limit for population seems to be more related to architecture (tech debt, a design made 20 years ago that might be hard to change now) related versus hardware capacity related.
It is also quite possible that they had hardware reserved for future projects, such as a new "bombadil" type server or a completely different server project idea they came up with, etc.... and that now they have decided that they should use the capacity reserved for that to a new regular server instead. This last bit is of course complete speculation.