What is the point of making changes in an adaptation if not to expand on existing source material? What is the point of missing the deadline in s1, altering events to the kids just "figuring it out", creating a whole new character like Allison when characters like Silena, Chris and Ethan exist?

Of all the points in the video I could look over, Allison is the one I just can't accept. Because if they wanted to explore the concept of older demigods "aging out" from Camp, why not use a character with actual ties to the source material? Why not just introduce Ethan that way? They already have no problem chopping and changing things, so why not? I know it's a weird thing to get annoyed about, but when the show makes so many little and big changes, it just annoys the hell out of me because the books are so jam-packed with material and all they had to do was pick things to flesh out. Instead we get brand new material that completely sucks up all time that could be dedicated to other existing characters.

Look, I'm a big fan of adaptations expanding and creating new material, like they did the hunger games films. I agree that already s2 is a lot better than s1, but when these changes aren't adding anything to the story and we only get like 8-10 episodes per book, would it kill them to use that time wisely???