Yes, very useful. It surprises me that the wide availability of flight tracking websites and apps hasn't done more to kill off the chemtrail myth. You'd think that the ability to easily identify the planes leaving trails in the sky as familiar commercial airliners would have a huge impact, but we still hear the nonsense about "unmarked planes" etc.
I think there are two reasons for this:
1) Not every flight shows up. This will gradually reduce as ADS-B becomes more widely used, but there will always be "mystery" planes such as private bizjets and military flights, that people will find suspicious.
2) People don't find the flight trackers very easy to use. I think a lot of that is down to misunderstanding where in the sky planes are, and expecting to find them low and nearby when in fact they are high and far away. Perhaps you could have included your "how far away is that contrail" graphic, as a lot of people seem to look in the wrong place.
(I have a pet theory that quite a lot of conspiratorial thinking stems from poor 3D/spatial awareness - I first pondered this when discussing Apollo photos with moon hoaxers. But that's for another topic...)
