Many years ago when people rode alu- and steelbikes weightweenies used to drill holes in parts to save weight. Always the easiest and cheapest way to save weight.
Then when modern carbon fibre frames and parts came weightweenies changed parts for carbon, tuning things like derailleurs with dremel and new carbon parts and alu screws. A rear derailleur at 130g and brands like Extralite, Tune, b-t-p, Carbon-Ti, Schmolke and THM Carbones was the thing. AX-Lightness and MCFK came and pushed it further with really light carbon parts and frames.
Then we came to now. When people buying a Tarmac, SuperSIX Evo, R5 or a Colnago C59/60 with Enve wheels, Sram Red groupset but with Clavicula crank and Praxis (!) chainrings. Enve stem, seatpost and bar, or 3T. It all results in a 6kg bike and they call them self Weightweenies. Without change of a single screw or even touched a dremel.
Team Sky talks about this:
What happened to that in cycling. Why are people on Weightweenies using heavy Praxis (I know they are good but anyway) chainrings when Extralite, Carbon-Ti or Tune is so much lighter? Why aren’t people putting a dremel in their Dura-Ace 9000 or Sram Red22 rear derailleur, or even changing pulleys? Why aren’t Extralite bigger and people using Tune U20 QR? Why are people talking about clinchers? Can people even spell to Schmolke?