I thought on this for a day and decided to weigh them. Hard to weigh completed guitars so I just went with my old fishing scales — not perfectly precise, but close enough. Two of my Jazzmasters come in at a fraction over five and a half pounds (that's the full guitar, hardware and all) and one is a fraction under six pounds; conversely the lightest of my equally-solid Telecasters is a shade under six pounds and the rest of my Teles and Strats are all north of that. (Not including hollow guitars.) For reference one of the lighter two Jazzes is alder and the other is ash, and the heavier one is ash; all the Teles and Strats are alder.
So I continue to differ. Again, it may just be sheer coincidence that I have particularly light Jazzes and heavier Teles/Strats/LPs/others, but I can say that at least among my collection, the Jazzes actually are lighter, period.