Well, look at it this way. At least you know in advance that the guy is not interested in black guys from the beginning instead of you messaging them and thinking there's something wrong with you if they never reply. People have a right to their preference, whether it's just that or racial prejudice.
I'm latino and I've experience the whole "sorry not into latin men" but I'm not going to get butt hurt over it because there are plenty of fish in the sea and many will come along who do like you not only for your race, but you.
Just because you can't find a guy on a dating site, doesn't mean you won't find one in real life.
The best part about meeting people in real life is that even if they're not normally into your race, you stand a better chance of them changing their mind through meeting you than you would from them reading a dating profile.