There is occasionally some whining and teasing about the way the modern FNaF fandom concatenates words into cute little names to refer to theories. In some cases, I understand this. They can get obtuse, like in the case of "Alter-S" theories. I do think it is ideal for the names to tell you something about their meaning. Many particular theory names are bad. However, the general practice of using theory names is something I want to defend.
There is the common complaint of "why can't you just write out the whole thing". For example, it seems that MCI85 could more effectively be written as "the MCI happened in 1985." It seems that way, but on closer consideration, it is obviously not true. There is an important qualitative shift which takes place when creating a theory name. "MCI85" is a noun which refers to a theory holistically as a conceptual object. "The MCI happened in 1985" is, on the contrary, a statement of the theory's contents. Referring to theories as conceptual objects in their own right is a very useful thing to be able to do, hence why every academic field comes up with names for its theoretical systems. To refer to the theory like this in ordinary language would look like: "the theory that the MCI happened in 1985." This is practically an entire sentence. And consider that, when you are writing at length about theories, you will likely need to refer to them multiple times in succession.
It is not only inconvenient to write these things out, it is actually detrimental to understanding. When you're trying to understand something complex, it is incredibly useful to be able to block together concepts into compressed units. It is true that in mathematics, for example, theorems can often be obtuse and difficult to understand due to technical terminology. But if, rather than using special words, we wrote out whole definitions each time, I do not think it would actually become easier. Having to parse entire sentences and actively think through each detail over and over takes more mental effort than you may appreciate, as it adds lots of unnecessary variables. We block together concepts into abstract units for a reason: It is legitimately helpful.
I suspect most claims of theory names' impracticality are reverse-engineered from feelings of silliness or embarrassment when using the terms, without much serious consideration of their utility. But the naming system has caught on so strongly in spite of this for a reason: It is a useful way to refer to things, even if it isn't obvious why.
Now, there are some cases where it really isn't much more practical as simply shorthand. Consider "SLbefore3". You can state the theory's contents as "SL is before 3", and you can refer to the theory as a conceptual object with "SL being before 3". The difference in convenience is very minor. But I still think there is a substantive value to using the concatinated theory name. Concatenating the words together without spaces lends itself better to thinking of it as a cohesive unit, and using the typical theory name shorthand aligns it syntactically with other theories, holding them together in the same mental category. Having a consistent convention for referring to things is useful for all sorts of reasons. It is better to have a naming convention which is used for all theories, than a naming convention which is used for all theories except for the ones you've decided don't need it. If you are a programmer, you will hopefully appreciate the intrinsic value of maintaining conventions when working with complex conceptual systems. It reduces unnecessary mental labour.
Coining a new term for something does, in a very real sense, create a new conceptual framing with which to think about the subject, coloring one's understanding of it. Technical jargon does serve as a barrier to entry for technical subjects, but it isn't used for no reason- when you need to talk about a subject a lot, it is simply better to have a specialized terminology. Laypeople tend to have really dumb misunderstandings of quantum mechanics largely because ordinary language is not designed to describe it, so when the math is translated to ordinary language for popular science communication, the concepts become horribly disfigured, creating lots of unintended implications which cause confusion. Of course, FNaF lore doesn't need quite as specialized an ontology as quantum mechanics, but the effect is still there. Consider, for example, the use of the words "agony" and "remnant" in popular FNaF lore discourse, and how, despite being technically functional words to refer to canon concepts, they nonetheless tend to frame the discussion in a misleading way, which systematically generates misunderstandings about the story and its mechanics. When you use the word "agony" in a FNaF context, you are dragging in a series of implications and assumptions most theorists have picked up, even if you don't intend to do so. This is why I prefer to talk only in terms of memories/emotions and spirits, rather than remnant and agony. (It's also why I coined new terms for Network Theory.)
That's all. I didn't realize I had so much to say about this until I started typing and kept thinking of things to add. I imagine a typical response to this analysis will be "who cares". My answer is, I care, at least a little bit, because I think ontology is important, naming systems are cute, and whining is annoying. I hope that you care too, and that you enjoyed reading.