For me, the starting point that makes a lot of it way easier is to focus on layering. Anyone who lives in the Bay Area will instantly understand it: you don't build outfits for different weather, you build outfits for all weather that just depend on how many layers you've got on. For example, no cold-weather coats: instead you pack a feather-light and very foldable rain shell, layer it over thin sweaters for cold weather (multiple, if it's cold enough), and wear it directly over a light outfit for warm rainy weather.

As the article mentions, good fabrics (like merino wool) can go a long way.

(1) Reliability and flexibility being foremost. Not having to worry about lost luggage. Itinerary changes are much easier when all your stuff is with you and can fit on your lap or under your seat. Then comes the comfort and speed. Being able to take the stairs or not blinking an eye at walking an extra half mile go a long way towards making travel enjoyable.

With my undiagnosed ADHD I usually start an hour or two before my airport cab.

My problem is not what to pack or that I pack too many things but to actually begin the process of packing.

I bring a week's worth of thin clothes that layer. If I need more, I'm either washing by hand or using a service. Basic toiletries, an e-reader, phone, keys, charger bricks, a notebook/pens, daypack. It fits into an underseat backpack with room to spare.

This has scaled fine all the way up to multi-month scientific expeditions in remote locations. Sometimes I need to accommodate specialized equipment like formal clothes/shoes, camera bodies/lenses, excavation equipment, tent, water purification, sleeping pad/bag, etc, but that's solved through the magic of bringing a slightly larger bag.