The deadly poison buff has overwritten all other poison combinations. In other words, if you aren't using Wound/Deadly your gimping your damage. The proc rate on your Wound weapon is about the same as running Wound/Wound.
So its near as damn the same damage + a powerful dot and most importantly you keep MS and Crippling on the target.
Therefore everyone is turning to envenom. Not because it got "OMFG BUFFED TO HELL" but because it wasn't possible before. Not having Wound/Wound was a huge disadvantage.
Here we have a couple of other envenom myths that are not correct, talking from an RMP PoV
1. "Everybody runs envenom"
- no, a lot of people do, but plenty of top players went back to the old doublewound/Evisc specc.
2. "You are gimping your damage if u dont spec envenom"
- this is also incorrect. the envenomspecc dmg will only be superior if you sit on a target over a longer duration, which you rarely do as RMP RMP's use the opener to gain momentum and force cooldowns. you need to have a very good burst in the duration of the sap/opener. unless your extremely lucky with DP applications, you wont stack 5 very fast, and using double wound will give more dmg than wound+deadly. the envenom damage will also probobly not be that high in the opener due to lack of CP generation, and a lot of times the burst gets fucked cus dp failes to apply and u cant use envenom.
using gouge between cs and KS is also an important point, because it allows your partners to dispell/CC/pop cooldowns while the target is unable to do anything so that they can get done with their other stuff before kidney lands, thus ending in longer uptime on the target for you partners. (also gives a nice window to use ToTT, since as RMP it's most likely your partners havent gotten time to DPS before CS is over