Because they lack common sense.
It would be one thing if the devs clearly went for speed (and lacked quality) and delivered a shitty update after years.
But it's obvious they are investing a big chunk of time to give quality art with a point-and-click real game feel that they have a clear vision (yes, even if the story writing seems confusing at times, no one is perfect and they are improving it).
Idiots complain and can't even comprehend that the devs aren't developing the game exclusively for them, specially if they aren't contributing with either decent feedback or financing this.
Nowadays, I think most of complains come from "meme status" gained overtime in these forums / communities, that people have seen artists that can't handle being 100% invested in game development, and in the end fail to deliver, or change the scope to something manageable for them.
Nah man, it's just that most people compare the game's development speed to other games and are able to come to the conclusion that the team behind innocent witches is at best extremely badly managed and at worst outright milking patreons by putting in 10 hour work weeks.
The devs can make as many promises as they want, but even in the past two year, where developement speed has skyrocketed from before (at which point it was non-existant), only 1 sex scene has been implemented every 4-6 months.
For example, iirc last year in december the hermione handjob scene was added and this year that god-awful minerva scene plus the susan titjob was added (both hermione and susan using the same background as the old scene with ginny btw). If you're a 10$-patreon you're paying them almost 120$ to add two, maybe three scenes a year. Something even high quality games (e.g. What a legend) include in a single update plus more (way more in fact).
Of course the art is top notch and way above most other games art quality, but 4-6 months for one scene? Laughable.
Their ability to keep patreons hooked via progress reports is amazing though. It's all empty promises of course, but who keeps count, right? I'm still waiting for the new luna and daphne mini-games that
barely didn't make it in a patch maybe a year ago.