Fenoxo once talked about how hard it was to commission people to write certain things for his game. He states that people would just much rather write a character with their own fetishes for free, than write some other character for money. The vast majority of freelance writing for TITS is covered by private commissions, or funded by the respective writers own patreon. A good majority of the stuff in TITS wasn't even funded by Fenoxo's patreon, but by a third party.
And when those writers disappeared, or pulled their projects, is when the backlog started. And why the writing for the game is so scattershot in places in terms of events and NPCs--everyone wanted to get their super special snowflake NPC in the game at the start of TiTs, but few wanted to see these projects as things they'd need to continue contributing to, so when they left there was no one left to take over. It's only been in like the past
handful of months that Fenoxo re-opened submissions, and even then it was only for established characters, because their backlog of "things to fix," got so long. (Fenoxo was also going through a divorce, iirc, when a lot of the bitching about content started and people started leaving. He's able to work full-time on TiTs through patreon, but I'm pretty sure--like you mentioned--other prolific writers aren't in the same boat.)
As someone who writes for a living, as well, I want to also try and make it apparent how hard it is to even be creative when you suffer from depression. Everyone thought at the beginning of the pandemic that this would be prime time to get shit like novels and projects done... but then we all quickly figured out just how difficult it is to write when you feel like your entire life is a shitshow and the world might end tomorrow.