There is some weight weenies in touring section?

Not quite sure of the point, as the weight of my gear typically dwarfs that of the bike. That said, I'm certain there are some custom-made titanium touring frames that are exceptionally light and durable, but by and large randonneurs are typically more proud of having the heaviest bike rather than the lightest. Maybe 26" instead of 700C just for weight savings?

I think, if you have light bike you can make more kilometers a day then you touring

I agree very much!

Asking blankly for the "lightest touring bike" is a bit hard though, as what constitutes touring varies a huge amount, and type of roads travelled, climate, logistical constraints (ie, do you have to cycle hundreds of km at a time between water sources and food, or can you just get away with a small bike bottle and buy food for each meal because the place is so densely populated), weight and size of rider, and weight and volume of equipment carried, your ability to maintain the said bike, are all some of the decision which factor into what bike is an appropriate touring bike for you.

I have seen some people tour, however, with some pretty light set ups. In the future, barring financial restrictions, I could definitely see myself touring solo unsupported and camping on the way, on a bike that without gear weighs close to the 6.8kg UCI limit. If I didn't care about throwing bikes away every tour, I'm sure I could go lower than that. Much of my ability to do so is down to my skills and experience touring in a lot of countries around the world, and ultralight hiking and camping. For example, I envisage I would have my gear load (not inc food and water) down to below 3kg, which is almost no additional strain on the bike frame, wheels and components. However, this set up would only be for relatively mild conditions (eg European summer, most of Australia in winter except the Alps) and if I was say, travelling in Africa, I'd have to add weight to both my gear and bike; at least 1kg to both, probably more.

Definitely the biggest inhibitor in my experience to people riding lightweight touring bikes in the realm of road racing bike weights is the weight of gear and food and water carried. Its not abnormal for a typical touring cyclist to have 20kg (or more) of gear strapped to their bike in four panniers plus a handlebar bag and a rack top bag, before they even add any food and water. While a road bike doesn't have to be that much stronger for an 80kg cyclist vs a 60kg cyclist, there is a big difference between a 60kg cyclist with 0kg of gear and a 60kg cyclist with 20kg of gear. The gear is static, not centred between the wheels, and can't ease itself over bumps and shift its weight around appropriately. The bike is now taking strain in a large number of directions, just just through the pedals and handlebars (and a little through the seat if you are sitting down) over bumps.

Igor Kovske has a great website on how he has done some ultralight touring.
Also see Peter's article on crazyguyonabike.com ...he did some relatively ultralight touring quite cheaply using an old road bike.
For getting your gear weight down (not inc Bike maintenance and tools) the best place on the WWW to go is backpackinglight.com

To be clear, when I think of "touring bike" I think of bikes setup for fully-supported tours, IE: there are rack and fender mounts, long chainstays, and tire clearance for 35C or bigger. For reference, my front and rear racks are 3.5kg total and each of my four panniers are 2kg empty. So really, what's another 5kg for a steel vs ti frame? Being a minimalist when packing will go way further than worrying about shaving grams off the frame, there are a gajilliion opportunities to shave grams when touring.

I've done a fair bit of touring around the world, fully loaded. My touring bike is steel. It weighs, with racks and fenders etc. approximately 30lbs. It has a tandem fork. It has Magura hydraulic rim brakes. Fully loaded, with 4 side panniers, a loaded rear rack and a handlebar bag it can reach over 90lbs. I had it custom made by a very respected builder in the mid 90's. At the time, he told me he could build it quite light. I voiced my concerns. He said the panniers etc were "dead weight", not moving around like the rider and so it would be ok. I didn't see the logic but I was new to custom frames back then and just said "well ok, if you say so". He built it. It was nice, impeccably brazed and everything was where it was supposed to be. I loaded it up and took it over the local hill for a test run. Guess what... He was wrong. Dead wrong. The thing was a noodle loaded up and I had zero confidence on descents. I didn't know what to do so I took it back to him to see what he'd say. It was much too large a frame for him but I threw some panniers on it and he took it for a spin up the road. To his credit, there was not a single bit of wishiwashiness on his part. He acknowledged the build was a noodle and remade it. This time he used a tandem fork, the downtube was much bigger in diameter as was the top tube (although the majority of stresses get transmitted through the downtube). Result: Perfectly stable touring bike fully loaded. Even feels a bit lively (lol, maybe springy is a better word). However, unloaded the thing felt dead. So, when someone asks if a bike can be too light (there is a fairly current thread elsewhere about this) my response is an unequivocal YES, it can. It's hard to find the sweet spot in weight given the choice of materials, rider weights, frame size, specific use etc.
But for a fully loaded touring bike, light weight is the least of my concerns.

_________________
My Colnago C59
My Special Colnago EPQ