You appear to have lumped all ultralighters together as inexperienced outdoorsmen who don't have an understanding of changing weather.
In the context of the OP, who by his post clearly is somewhat inexperienced, advocating an ultralight approach for someone who has yet to develop the risk assessment skills and knowledge in the outdoors is not a necessarily the best approach.
To make the decisions on what kit can be trimmed back takes experience. That needs to be learnt, especially as each individual has different abilities, fitness, tolerance to temperature, food requirements etc. It's not something to be learned to a suitably safe level simply by reading another ultralight enthusiasts posts online.
Being encouraged on an online forum to suddenly give lightweight tramping/hiking a try, by posters who have a lot of experience, runs the risk to the novice of cutting back on kit that an experienced person would not.
The OP can't jump online when he's caught out in his -50 and is freezing his tits off to ask all the experienced people what he should do now.
I'm not suggesting that he shouldn't experiment and work out for himself what works and what does not - on the contrary, that's the way to actually learn. But my posts are aimed at tempering that rush of enthusiasm coupled with lack of experience that might lead to problems.
though he mostly just uses an umbrella.
Are you taking the mickey? An umbrella? I nearly wet myself when I read that.
Clearly our experience of the outdoors is very, very different. An umbrella would be about as useful here as a chocolate frying pan. It is pretty normal to set off on a nice warm day at sea level, be hot to the point of needing to be concious of water intake, yet by lunch time be at around 1200m and leaving the bush line to be exposed to high winds and a wind chill effect that requires you to put on your warm mid-layer, exchange your sun hat for a balaclava and dig out gloves. If you keep climbing to the tops, at around 1500 - 1700m you might even find snow on a summers day. By the afternoon the chance of the weather changing to freezing windblown rain is high, the wet weather gear you have is not carried for emergencies, it's carried so you don't get hypothermia on the tops in the afternoon, not as a 'just in case' but as a definite requirement that you will use. This is pretty standard for a fairly simple day long tramp in the Tararua or Ruahine ranges.
You appear to have lumped all ultralighters together as inexperienced outdoorsmen who don't have an understanding of changing weather.
Not at all, note that I stress the importance of having the experience to make the correct decisions about what equipment is needed, and to have the experience to understand the conditions and the implications of your gear choice in those conditions. That is far from saying that all ultralight enthusiasts lack these skills. For those with that experience fine, the issue I have is with those that don't, or more dangerously, those that think they do, but don't (like the guy in the article). I also make the point that simply reading a post on here does not impart that experience, and caution is important.