My current little 80mm f/6.0 apo triplet weights 6lbs. In the past, it might have been lighter. Focusers and cells were cast/machined as opposed to extruded/machined and simpler (rack and pinion versus Crayford). Also, new focusers and cells being more complex weight more. In the high-end, even tubes for small scopes can be fully-machined and generally thicker and heavier than the rolled tubes of before.
This apo which I "created" using a cheap Sky Watcher 70mm achromat tube cut-down and a vintage brass-cell Taylor triplet lens weights only 2.86lbs, similar to my old Celestron/Vixen 70mm fluorite scope. Granted, the focuser is a plastic travesty, but it does work.