@Final i dont see it either. this prologue is one of the best i've seen for an isekai. fairly long,detailed, although it feels a bit rushed but its still just a prologue after all, you can see the progress in it and with a bit of tragedy at the end to truly get the story going. if i were to score it just for it, it would be a solid 8/10 imo (and im not one of those who rate stuff from 6-10 with 1 reserved for stuff i truly hate. to me an 8 is good to really good, not average). the only stories on top of my head i remember reading with notable prologues are isaac and fallen monarch (both web novels im really into), most of the rest are 2-10 pages to a maximum of 1 chapter and thats it.
now about those complaining, in this scenario there are 2 types :
1. the "bad ones", with the attention span of a dead fish and whose brain go into overdrive and then catches on fire if there is any depth to any story and so they start whining like little brats (just like i remember them doing in the aforementioned 2 examples)
2. the disappointed ones : those who, like me, liked how its started and tried reading the web novel. and let me tell you, this goes from 100 to 0 really fast.
i do hope the manga will take from the ln or, if that one is the same since i didnt try reading it, will change some stuff. because if the story will progress as is in its original source material(wn)....disappointment is not a heavy enough word for what you'll feel. it becomes the bland, boring, soulless thing it tried so hard to differentiate itself from up till now, just like any other low quality isekai out there. the drop in quality is mind boggling to say the least. but for now there is nothing left but to wait and see, maybe it will redeem itself.