Firstly, "multi-user chat kingdom" is a backronym that was not envisioned by the original authors of TinyMUCK, but perhaps by the users or developers of some future fork. TinyMUCK is notable for having a "Fuzzball" edition or fork, that powered FurryMUCK itself, as well as related worlds which hosted and catered to people in furry fandom.
Secondly, exactly none of these had a "combat system" of any kind. These were all derived from TinyMUD, written by Jim Aspnes at CMU. https://en.wikipedia.org/wiki/James_Aspnes
TinyMUD was a "social MUD" and its explicit goals were to be a glorified chat room, and a sort of "blank slate" for people interested in building their own extensible worlds, based on a pure textual interface. There was absolutely no "combat system" at all--in stark contrast to the other "MUDs" on the scene in those days, such as AberMUD, DikuMUD, and LPmud, which were arguably way more popular, way more violent, and way more into the "combat" or "PvP" or also PvE type play styles.
There was, of course, a "kill" command to allow one player to kill another. But the results of the kill were quite nerfed: the player was sent to their $HOME, and collected an "insurance policy" of pennies, which was partly based on the killer-determined "cost" to kill them in the first place. This wasn't combat by any means--basically, a way to sort of put an exclamation mark on a conversation.
MOO, though it was not derived from any Tiny* codebase, was also one of those "talkie" muds at its heart: it was an object-oriented, fully-programmable, extensible world-building server, where indeed, any combat system could've been implemented, if the players/programmers of a certain world agreed to include combat. But MOO was unique in giving a "barebones" server to program from first principles. So, no, none of these had combat systems, and that's their chief appeal.