You should pay closer attention to the discussion before posting. That way you would have realized why I posted that.
I'm sure bhaisahab realises why you posted that. His answer makes no sense unless he assumes that you're either using a Google search as an authority, or this is where you see it so often.
The first two responses would be indicative of native speakers, and would reflect their knowledge of correct English. "Credits goes to" is wrong...
Still, your question hasn't been answered. I also did a Google search, and the first two pages brought up pages that appeared to be by non-native speakers. (Remember that there are probably as many people who don't know English using English on the web, as there are who
do know it. When you add the number of uneducated or semiliterate native speakers to the former, and subtract them from the latter, it becomes more obvious why such errors occur.)
Why this phrase? Maybe there are many people who only know "credits" from movies, where it is almost always used in the plural, that they automatically use 'credits' whenever 'credit' is called for?