It's not just for fun, you can get a good sense of the algorithm. One of the things it is somewhat prone to is some weird looping, like this: https://www.reddit.com/r/SubSimulatorGPT2/comments/d1nwdg/if... in which the algorithm generates the sentence "Toss some leeches around and wait 'til we get there." (no, it does not make any more sense in context), and then repeats that sentence nearly (but not quite!) exactly 23 more times. (I expect this is a consequence of the way it is tracking some internal state; I assume these sentences are strange attractors in some sort of state that is getting iteratively modified.)
You can also see that while it picks up some deep structure, a check of anything trained on /r/jokes (https://www.reddit.com/r/SubSimulatorGPT2/comments/d055mt/a_... ) or /r/math (https://www.reddit.com/r/SubSimulatorGPT2/comments/d1yz1e/ho... ) the algorithm is definitely unable to deal with deeper structure right now. The /r/jokes bot is humorous in its complete lack of humor, I mean, well beyond any sarcastic snark about how unfunny /r/jokes may be. It has the structure of jokes. There was one recent one that even asked "What's a pirate's favorite letter?", and the bot had noticed the answer was being given in the form of letters, but I don't think a single instance of the bot proposed "r". But it does not understand humor in the slightest. Of the several dozen attempts at jokes I've at least skimmed, I believe it only achieved something that was at least recognizable as an attempt at humor once, and it still wasn't that funny. Likewise math. It's got a good idea there's these "prime number" things and they're pretty important, but I've seen at least half-a-dozen wrong definitions of what one is.
It's a very interesting algorithm. It's a great babbler. But on its own, it's not a great solution to generating text. Although it may very well be able to generate text that can pass a casual skim text, as the article suggests. Still, it takes human curation to get that far. Any human that can read is going to guess something's inhuman about repeating "Toss some leeches around and wait 'til we get there." 24 times in a row.