It’s generally pejorative and obviously meant to be here.

"Nothing is obvious unless you are overlooking something". At least as far as my usage of the word "cult" is concerned, it was indeed not meant to be pejorative. Actually, I didn't even use the word "cult". I modified a prior use of "cult" by typing "subcult".

You choose (feel free to replace that verb if you don't like being credited with having a choice in this case) to interpret "cult" as pejorative and even obviously so in this case. I will make no speculations about whether or not the use of "cult" that I copied from was meant to be pejorative or not. However, it did not appear "obviously so" to me. But I freely admit that this could be mostly due to my choice (you can't change this verb, though) to try to avoid interpreting text-only communication as heated.

In my experience, people are already naturally too prone to perceiving malice in text-only communication, especially if that communication is disagreeing with something that the reader either wrote or empathizes with. So I choose to expend effort in the opposite direction (and sometimes do it without effort).

I also tend to use colorful words. I am much more likely to inform you that "I stole your stapler" than "I borrowed..." when I return it to you.

And I perceive the word "cult" being used a lot of different ways. It can be vanilla (an "actual" cult). It can be critical, even pejorative. It can be playful ("I can't make it to 'dungeon' cult tonight"). It can be very mildly critical, more like hinting that things might be coming close to being deserving of criticism.

I think I am most likely to use "cult" simply because it is short, ascribing no positive or negative inflection to it. Simply conveying that what is being discussed is a group of people who have some shared interest, likely with at least a bit of devotion or emotional attachment involved.

And, lacking some apparent emphasis, I am likely to interpret the word "cult" that way as well. When I've heard people use the word "cult" as a real pejorative, they put rather dramatic verbal emphasis on the word. To use "cult" as a pejorative, the word has to be spat rather than said (IME, though, not counting when people are using "cult" for its literal meaning when talking about some flavor of religion). I choose to not assume people are metaphorically spitting when I read their text.