Does anyone still attempt write merit-worthy reviews or have people lost interest in doing that altogether?
I have written about five reviews. Although I haven't received merits for them, I did hear back from developers twice. The most important thing was that the feedback I left got through to the people whose games I was reviewing.
Is there a special place to write merit-worthy guides or reviews? I've never seen one.
Play some old games from 2008-2011, and click "show more comments" until you start to see long comments from 5 or more years ago if you want to see merit-worthy reviews. Don't bother with the ones with thousands of comments because that's too much clicking and scrolling.
One of the most recent merits I received for a game review was for This is a Work of Fiction. The comment was made on April 10, 2011. Disqus makes it harder to find comments, so I chose one that has under 1000 comments on it so the scrolling wouldn't take too much time.
I also found @Gretgor, who has 14 more merits than forum posts. This could be a record, but it's equally possible that there's someone who has more than 14 more merits than they do posts.
More people went for them when AP existed, so your chances of earning one were reasonably high if you wrote a good enough review, but that doesn't mean they aren't still awarded. You can always try and see where it goes.
A merit leaderboard may encourage people to get back into the reviewing business, and site contest participation would increase. It would be years before anyone passed nick_coolhaha, but eventually we'd see some people with 50+ merits who didn't join before 2010. @ivanxxxxxxx is the only one I've seen so far who fits in that category.