We're comparing deoxys and skymin in terms of revenge killing only. Movepools and everything else about DX-S are impossible to compare to Skymin.
-Even with revenge killing, switching is an option. I realize that this same argument could be made for Deoxys, but the type coverage means that whatever switches in risks SE damage. Spiritomb is the best counter to revenge killing Deoxys due to Sucker Punch / Pursuit + Psychic immunity + no weaknesses.
-As I've pointed out, Stealth Rock makes Skymin even more susceptible to being picked off by priority - after all, it DOES have to come in to begin with.
Yes, it was movepool that made Deoxys uber, but it was not so much for the revenge killing part, rather its effectiveness as a lead was too good. This was realised when DS DX-S became popular. People who didn't realise the potential of that set believed Deoxys should've been OU.
-This is somewhat true. As soon as Deoxys was declared OU in the initial vote, its usage on the ladder jumped incredibly, evidence that its potential as a revenge killer was well recognized. DS Deoxys is good, but if I wanted to I could use DS Azelf and have similar results (since Azelf is still pretty fast itself).
It's also interesting how you ignored my "ice shard crippled her" comment. And I never posted "it's more powerful and has better STAB than DX-S it must be Uber." I'm only comparing the two revenge killing skills (and I never said Skymin should be uber). If you're going to get insulting (and don't), don't make up complete bullshit.
-You did, however, mention the secondary Air Slash STAB as significant. While this is a factor, the relatively weak power of Air Slash means that it isn't doing too much damage anytime soon without stat modifiers. Notice that your example of 2HKOing bulky Gyara without Stealth Rock is only true when there is indeed a sp.def drop. Unfortunately, this is the case in many circumstances.
For my current team (and i was one of those who had some major changes in team from dp to plat), I have Scizor, Blissey and my own Skymin for Skymin. Ironically, I lost my last game by getting swept by a Skymin (it came down to a point of Skymin vs Skymin), as Scizor was in health range to be KOed by Air Slash, and the enemy paralysed Metagross haxed my Blissey with a crit. I prefer uber battling, in which im #3 at the moment (formerly #2 (but my ranking is irrevelant)). I don't play much for a while due to exams (not much every day). i've been playing since the start of this year on shoddy, used to be on the ou leaderboard before plat was out (official shoddy, before smogon supported shoddy).
-Playing on the Uber ladder means nothing when it comes to OU. In the scenario you depicted, your Scizor was weakened and Blissey was haxed by a critical hit (which is irrelevant as Metagross has no trouble trouncing through Blissey). Of course you will have a more difficult time against Skymin when your main answers to it are not in the best condition (Skymin vs Skymin was a speed tie, so that isn't evidence either way).
Now, how much have you played (and don't make up bullshit)?