Well, probably because they want you to give them high ratings regardless of the quality of their story. Most of the time, that's usually what happens to review swaps. Writers giving each other high ratings. Like I'll give you a 5 so you also have to give me a 5 even tho your story and mine sucks big time. It's like they're just licking each others ass.
That's why I think review swaps are totally unreliable. Some don't even try to read the story and directly give it a high rating saying 'your story is good, blah... blah... blah... blah...' so the one they gave a high rating to would also give them one.
I read one of the reviews you made. It's comprehensive and constructive. Definitely not something you would often see here in WN. So good job on that. 🖒 I hope your hard work won't get deleted again. If it does, just stop giving reviews. Because you're probably just wasting your time.