I think FTN owes much of its success to being a pioneer of the no-ratio system. It isn't a huge site with a tremendous archive of well-seeded torrents, but that's not really the point of torrents in my opinion (and that of some uploaders I've chatted with).
But I've noticed in the last year, since they've opened up a lot more invites, that the explosion of seedboxes has affected FTN as well. I've noticed that most of the new users have quickly surpassed my fairly high upload amount. These people are pushing out TBs within a few weeks/months. How? By downloading everything popular in every format available and every pack and then even cross-seeding on other sites. Why would anyone cross-seed a new torrent on FTN? There is no ratio and the guise of "I'll help seed" is bogus. It's all about the epenis.
So I've noticed in this time that there are probably a lot of peers, especially in the first wave of snatches and first couple of days, that are not at FTN to benefit from the no-ratio system. In fact, the no-ratio system should be discouraging them from downloading at FTN. Yet, the peer numbers overall are inflated by the seedbox phenomenon.
I've only been a member of PTM for a few months and frankly don't use it all that often. Plus I cannot observe the peers list on site (and am not familiar with most of the older users like at FTN). However, I think their variation of the no-ratio system works great. Most of the users are on home connections. Some are on shared seedboxes or decent dedis. Overall this means speeds are a little slower, but with the larger userbase, the swarms are still really fast. I'm sure there are some cross-seeders and other forms of kids playing with their seedbox there as well, but from what I can see, there are still a lot of people benefiting from the no-ratio system.
All that being said, I think you're misinterpreting two key points.
1) No-ratio systems are not intended to prevent hit and runs.
No-ratio systems are intended solely to encourage leeching, especially for slower home connections and those who come a few hours after the swarm. The reason a number of torrents are 1/0 is almost always because it is something nobody really wants (some lame tv show) or it is really old and being kept alive by one of the handful of people who everything forever no matter what.
2) Most new trackers fail. I think there are more than enough trackers out there. There probably were more than enough a year or two ago, but they keep on coming out. Just going no-ratio will not save any site, no matter how awesome it is in theory. I think one of the biggest problems in this over-saturated marketplace is the fact that so many trackers make it difficult to even hear about them, let alone get in. Keeping things small and private is great, but not when the server costs are still high and the lack of torrent activity makes people who finally do get in go, "that's it?"
I truly believe in the no-ratio system. By having some stats and rules in place and providing good content, you'll encourage people to be responsible users. They might not seed forever, but if they seed for a few days or close to 1:1, I think that's pretty damn good. I don't know if it would work on a big site, but I doubt it will ever be implemented. Big sites are big because they are established and most of them are not going to radically change their ways.