I'm relatively new to keyboards but some things I've seen people rationalize whilst researching and browsing:
20%/30%/40% boards: "I use multiple layers and that makes me more productive, my 20 switch keyboard has more "keys" then your fullsize due to the use of layers!". Maybe I'm still a noob, but couldn't you program custom layers and layouts on 60%/65%/TKL/Fullsize as well? Why would a smaller board with custom layers be more productive then a bigger board with custom layouts and layers? Having extra desk space is definitely a plus though.
I believe that the best argument there is that the keys that they use most are exactly where they want them without having to entirely leave the home row (like arrow keys, etc). Otherwise, yes, the reasoning doesn't really objectively go anywhere else besides that and size. Another thing repeatedly mentioned is it has some sort of ergonomic benefit, in specific circumstances, like hands being closer together when mousing/gaming, making up for some kind of handicap, etc. I find that to be almost intangible, certainly at least personalized, if not entirely subjective. Maybe not though.
Personally, I recently found that my preference for ctrl being exactly where it is on a modern keyboard, and being dumbfounded by the preference of some to have it where Capslock traditionally is, may itself be a bit of an anomaly based on the fact that I have pretty long fingers and am double jointed. There are certainly exceptions to every rule, and even rules that should not be so.
Aviator cables: "I switch keyboards often so the use of an $100 aviator cable will preserve the keyboards USB plug". Sure, but wouldn't a USB hub or USB extension cable with a shorter 6" USB cable do the same thing for $10 and be more practical?
Aviator connectors, themselves, are not very expensive. making your own cables is cheap. Those pointless inline aviator connectors ... in an otherwise normal USB cable don't have much going for them in the practical department if you ask me. I would worry more about the weight they add to the more fragile connectors on either end, and physical damage to them, than the number of insertions. I have never permanently damaged a USB connector just by plugging it in and unplugging it before. I did recently have the plastic inside of a USB type A connector (my first of any kind) break off due to the weight of my custom cable, over time. In that way, USB hubs are better than fancy aviator cables. I like to add female GX12 aviator sockets to the cases of the keyboards I customize, then I can literally pick the keyboard up by the cable. That makes a custom cable worth it. Those blingy ones, not so much.
"Holy Pandas are the best switches! the tactile bump is nice, smooth and round! Other tactile switches such as T1s, Box Royals and Zealios are ttttooooooo tactile and just jarring!" I wish I could afford some Holy Pandas to try just for the hype, but I feel I might just be disappointed. I also understand different people have different taste, sight, hearing, feeling and what I sense is different from what someone else might sense and this is why people have different preferences.
Yeah, a general consensus, if primarily based on experience, is good, even if it is subjective. We only run into problems when too many people support that consensus because that's what they heard without experience and/or are influenced by said consensus over their own perception. Even if this were never a problem, you still need to find what you prefer. The switches popularly considered to be the best in any category should merely be good reference points for your own comparison.
There's no one switch to rule them all. There are people who love Cherry MX Brown and swear by them compared to anything else they have tried. Personally, I can't think of much else worse than MX brown. I, personally, love capacitive buckling spring. Others hate it in spite of its feel because of the way it sounds. Some even think membrane buckling spring feels better to them, even though the conventional wisdom is that capacitive (IBM Models F) buckling spring is superior, etc, etc.