I consider the topics you posted as somewhat spams and not worthy of getting +karma. I bet those posters didn't even put an effort in adding their input to the topic, it's just copy-paste and goodbye. Posting a link doesn't also qualify for quality topic. They're just trying to promote a product. You should check their post history and you'll know what I mean.
About karma generosity, I give it to someone who can actually engage in real discussions. Not copy-paste from articles and not rehashed comments/posts.
You reminded me of the time I got a private message from someone asking to give him/her +karma since it's free and because he/she game me one. Can you imagine how many people this member has message to get +karma in return? That's like trading. That is probably the reason why I see some accounts with at least 10 +karma but they post mostly one or two liner low value contents.