BKC, you do have a point but you're really nailing the head of something that doesn't really matter. The person who really hit the spot was the one that mentioned drizzle being a free turn and this is essentially what pushes it over the edge. Without even wasting a turn you are nerfing fire attacks by 1/2, boosting water by 50% and activating a plethora of abilities and otherwise innaccurate moves for your whole team, for the whole match, unless challenged by another weather.
This wouldn't really be a problem if (in general) the other weathers could keep up. But let us consider that for a moment.
1. Rain has just about anything and everything to deal with anti-rain threats. Because the only pokemon that are nerfed by rain are those that run fire attacks and plenty of pokemon enjoy rain or don't mind it, rain can run almost anything it likes to counter other weathers. Consider things that give rain "trouble", here are a few:
Gastrodon - Rain has Ferrothorn on most teams, otherwise things like Breloom, Latios and rotom-w all enjoy or don't mind rain.
Tyranitar - As headache inducing as this pokemon is for rain, rain has almost anything available to it to switch into the 'tar, from Keldeo to Toxicroak to Breloom & Jirachi
Trappers - The irony here is that Dugtrio traps Ninetales and Tyranitar much better than Politoed but rain is so well off, you often won't need to bother running Dugtrio, now if only sun had that luxury! As for Gothitelle it is generally a liability as it has incredible difficulty switching in, and can't ohko defensive politoed nor can it survive moves from offensive politoed (except.. focus blast? lol)
Celebi - Rain has Jirachi (u turn), Tornadus, it can easily fit basically any common turner like Scizor - who will never be ohkoed by any move Celebi runs in rain - with barely any effect on the team synergy.
Ferrothorn - This is probably the most difficult for rain to break through because its defenses are simply so good, but between moves like scald flying everywhere and a pokemon with stab fighting moves or powerful attacks it is eventually worn out.
2. Lets look at what sand and sun have... Basically any pokemon that is on sand used to counter rain, with the exception of Gastrodon & lol Cradilly will be being buffeted by the sand storm and thus nerfed in their home weather. Countering sun is a little more easy as sand teams either tend to run 'cent to spin block or eventually win the weather war with Tyranitars inherent advantage over Ninetales (can switch more freely and has better stats/movepool both defensively and offensively). The major problem sand faces is that it really can't run much sweepers as their team slots are usually filled trying to complement weaknesses and counter other weathers, as such we don't see much Stoutland or Sandslash or even physical Landorus-I in OU (their offensive power is not compelling enough to justify using them on a sand team to most players), whilst rain can easily take a pick of a variety of sweepers that can use the weather boosts. Terrakion is really the only "common" sand-improved sweeper I can currently think of.
For sun your teambuilding options are incredibly limited, as discussed multiple times in this thread. I'll just be brief on this as it has been done to death but a good sun team NEEDS to have MULTIPLE pokemon JUST for dealing with hazards and sand and rain. Of course a sun team with ninetales/sawsbuck/venusaur/scarfdarm/forretress/volcarona will absolutely steamroll a non-weather team in this current meta (since everyone overprepares for rain, yes I have been steamrolled by an oponent of low skill with the above team) but will fail the moment it meets other weathers.
3. Weatherless teams can not deal with everything at once. This one is incredibly obvious, as mentioned above, a weatherless team will be steamrolled by an offensive sun team stacking sun sweepers as they are so rare and it is impossible to prepare for them without compromising pokemon that deal with other weathers and classic comboes like drag/mag. Most weatherless teams I see these days tend to overprepare for rain and as somebody who also prefers to run weatherless sometimes its so blindingly obvious that they have weaknesses to threatening pokemon like Haxorus or Terrakion simply because they are doing their best to have a team that can hold its own against rain. It'd be interesting to see how weatherless teams prepare for sun in a meta without perma-rain as I suspect they will be much less of a threat (except perhaps 'saur)
I think instead of beating around the bush about "match-ups" we should be actually discussing issues associated with the abilities (and not how "match ups" are shaping the meta), since this is what the poll is really about. Don't get me wrong we are still technically discussing match ups but we should be hitting on the head of the issue, not beating around the bush and running circles with the arguments without actually discussing the "issue/solutions" and not the "extended problems".