Originally Posted by RChung

Many people say this -- and they'd be right. But the real reason this is so is because training FTP is one of the least demanding applications for a power meter. That's why people have long been able to train successfully without a power meter. There are some things that are hard to do without accurate and precise measurements, but training FTP isn't particularly one of them. Many (but not all) riders aren't interested in doing those other things so for them a PM like the Stages will probably be fine. If you are interested in those other things, it won't be. No one (and that can sometimes include you yourself if you're first starting off with a power meter) can tell which group you fall into, or if your needs will stay the same over time or change.