It’s a tricky one this.
If someone asks for advice on what colour of suit to buy, it’s presumably because they’re not sure what is appropriate etc, so they look to others with more knowledge/experience. Fashion is obviously subjective, but there are a few fundamental guidelines/rules which can be observed for business/formal dress, so those tend to filter through to people and invariably end up being commented on at length in magazines etc (e.g. Esquire). If Esquire says “dont’ buy a black suit” it’s probably not them trying to be super cool and off the wall, since business attire has a pretty long and conservative history.
At the end of the day, people should wear whatever they feel comfortable in, and if that’s a black suit and short sleeved shirt, who cares what everyone else says you should or shouldn’t be wearing. Just don’t expect your views on business dress to carry much weight with those who tend to keep in line with more traditional (or fashionable) schools of thought.
A fashionable approach to things is just one approach, functional is another, some people would prefer a pair of cargo pants over jeans, short sleeves when it’s warm, or a nice pocket on their shirt to hold pens in etc. If you’re only wearing a suit because your boss says you have to, then none of this probably matters to you.