The "leach" argument is that while it is certainly a credit to the affiliate that they brought you a new member, where does the credit stop? The website in question is the one that is keeping that member a paying member. The affiliate just brought them in.

I realize there are all sorts of reasons to offer recurring as an affiliate program so I don't want to get into all of that, just that if the affiliate isn't bringing in any new members after (said amount of time) when do you start to say "why am I paying them for ME keeping my own members when they aren't doing anything for me now" type of thing.

I'm also not saying whether that statement is moral/right/wrong, etc Just giving one side.