Ok I am sorry I assumed you did - so thank you for not dragging me down :-D It must have been some anonymous jerk who doesn't have the balls to tell me what upset him and give me the chance to argue with him.
In comparison the MBP 2012 and a MBP 2016 do not differ in weight so much (1.4kg vs 2kg which is basically a package of flour) and if I am honest I don't really recognize the difference when carrying them in my backpack.
But it depends on the bag as well, because if you use a messenger bag for example the strain on the shoulder and the back is probably noticeable. Also many people like to carry their notebooks around with one arm / hand and of course this will be a huge difference then.
Some people like to use the Thinkpad X1 or the Dell XPS as a replacement but I don't have any hands-on experience with those.
I hope someone will recognize the gap in the market and jump in to produce 13 inch, retina screen uni-body metal notebooks with the ability to upgrade the parts and with all the ports you still need when not living in some bubble where magically everything was converted into USB-C overnight.