Gold on any kind of electrical contacts is just used to prevent oxidation...
Oxidation can cause interferences (think of analog audio or video signals) or completely prevent the current flow, not lower latency per se.
Everyone who thinks clears feel like rubberdomes probably never tried em or has numb fingertips imo...
And even if they would feel exactly like rubberdomes it would be still be a improvement (lifetime, possibility to use different keycaps, etc.).
The reason not that many people have boards with reds is that not that many boards were actually produced...
The ones that were produced sold kinda fast even tho they were priced higher than the black/blue/brown counterparts in most cases.
I guess the thing is that black/blue/brown MX switches appeal to broader audience, they are the the average-Joe MX switches, hence they are found on more boards, hence they are sold more, but that doesn't mean they are better than the others. Look at LCD monitors for example... Most people buy TN panels and are happy with em, but that doesn't mean they are "the best" (we all know IPS panels are the best, right? :D). "Most sold" doesn't equal "best product", also with things like our beloved MX switches it depend by a huge amount on personal preferences, and these shouldn't be mixed into a guide/review, STAY NEUTRAL!