No, I was not suggesting that one need to ask a favor with moderators or reviewers. Genuinely try to add them to your app community and constantly seek their feedback & update the app. I was not suggesting one-time marketing effort. More like create a community around the app which includes these reviewers or moderators.
This will give you a short time spike in installs. Nothing wrong with that, but it doesn't last and you can't play that card more than once.