Link submission gives more and more points but it is always not interested for the members to do so.. as we have to open other sites too and work more to create and write some thing related to the topic and add links and submit here.... it is some what a tedious process. People who are working on the site along with their normal work cannot be done such a long process.
Members who are idle will look for the money making activities rather gaining more points, so switching over to other sites.
Regarding reviews it is good to stay with IRC as we can generate good adsense revenue as said by Mr Vivek Ram Mhatre.Regards, RK - Some thing special