Hiking is a useful analogy but does not translate directly to cycling. With a pack you're carrying all the weight on your own muscles. On the bike you're carrying the weight on some rolling wheels. Cycling on the flat, the extra weight is not perceivable. Climbing is the only thing that is affected.
Someone mentioned a 20-25% of body weight limit for hiking packs. Most of my hiking is done as part of technical climbing so I use a 33% of body weight limit. That's 55lb max pack weight for me. This translates pretty well to the approximate luggage weight for a long haul bike tour. If you're touring in a rich developed country, you can save some of that weight by carrying less spare parts and tools. If you're ok with stinking like a hobo, then you can save some more weight by carrying less clothes. If you're ok with eating uncooked food like the homeless, then you can save weight by cutting down on cooking gear. You can go lighter and lighter and sacrifice as much as you wish. Eventually you can get down to almost no weight as long as you are satisfied with living like a wild animal. It depends on your personality.
Or you could just carry a credit card, ride a 14lb bike with zero luggage and stay in hotels every night.
It's all personal preference. As long as you are in a rich developed country, you can do whatever you want with no consequences. When you get caught with your pants down you can always get a bail out. If you try the same thing in some other remote part of the world, you may be in trouble.
Last edited by Yan; 09-07-22 at 09:53 AM.