Maybe I'm offbase here, but my impression is that wax & sealants are good for (1) creating a visual luster and (2) making it easier to wipe away grime when you wash the bike with soap and water. Presumably the wax/sealant is broken down immediately in spots like the bottom of the downtube and rear of the seattube that are sandblasted with grit on a wet ride. Works well for cars because they aren't with the exception of the front bumper & grill (and wheel wells, obviously), which I've noticed lose their luster almost immediately, and I've tried a lot of products. And you'll still need to get to those hard to reach spots to wipe away dirt anyway. I'm not against the idea, I just think it's hardly worth the thought you (or I, for that matter) have just put into it.