I think alternativeto.net is the database of software that already exists, many people use, and it would be better to focus on developing and promoting it, instead of creating new sites from scratch.
Alternativesto is old and has not improved much. I am yearning for a better alternative since iusethis has gone away.
If existence of a competitor stopped everyone from trying anything new, the web would be much more bland.
Even at this early stage, there's differentiation from alternativesto in their principles e.g. lack of downvote buttons, different qualification criteria for posting reviews.