Why? If you don’t wanna donate, don’t donate. If you think donating something rare is worth the coin, go for it. It has absolutely nothing to do with whether that person is a good donator himself or not.
Most requests are for junk DNA so that people can up their coins, other people prefer to get some DNA. Let them. They’ll find out soon enough that no one is going to give them irritator.
Personally, in the rare occasion that I really do need something rare, I offer a trade. Always works.
How does it benefit anyone if you know who donates the most? You’re gonna kick the members who you think don’t work hard enough? What if they’re very active battlers or darters? Or not. Is your alliance hardcore or casual? If the latter, then why does you question even exist?