>>42530611 (OP)
A lot of posters are carving out an exception for smut, as though that shouldn't count. This strikes me as silly. You don't have to appreciate smut, but as I see it, you can't fully appreciate the structural nuances of greentext without considering it.
Greentext is a format particularly well suited to porn and/or romance. It's great for clear and snappy back and forth, a dialogue with a lot of small scale stage directions. The alternation between green and regular colours naturally makes it very obvious which side is talking and the consistently separated lines makes it easy for detailed stuff to continually be happening without disrupting the pace. In other words, it's perfectly ideal for writing sex, and very good for writing the kind of one on one interactions that might expectedly preceed sex or follow from sex.
Now consider writing a scene involving five characters all talking, or trying to write a large scale battle scene. Both are possible, both can be done well, but now sticking to the greentext format starts making things significantly more difficult, rather than being structurally complementary.
So, if you're not planning to write smut, there's not much reason to choose greentext as the format beyond following board convention and wanting to post it here for the sake of the board itself. On the other hand you could choose any other format, which would likely be more complementary to what you're focusing on, and fimfiction will give you what's realistically a vastly better catalogue for your work to be stored and found.
Even in terms of the immediacy of having the audience in the thread lends itself well to porn, as a writer can guage reader interests as they post and adjust more dynamically than they could if posting full chapters to fimfiction. Most other subjects won't benefit in the same way from that kind of fine tune tweaking for taste. There's also how obviously condusive the second person perspective is to self inserting for smut, but that pov and its benefits aren't strictly exclusive to greentexts, plenty of fimfiction stories are second person just without any of the other constraints of a proper greentext format.
None of this is to say you can't write a great greentext that's entirely bereft of anything lewd, plenty have done so. However, for most other purposes the format won't be on your side in the same way as it would be for smut. It follows that greentext smut is the thing that endures, while writers who aren't interested in smut drift away from the greentext format.
