First of all, sorry for my bad English.
What you say is theoretically correct, but also practically wrong, I'll try to explain better.
We all know from 12 years Vanilla ret dps in low compared to the 2 best melee classes fury war and combat rogue (with same gear/consumables/player skill), but we also know that 40 men raid is not easy to full, even for top guilds, and not all 40 players are super pro elite players.
If you mind if a dedicated player ret deserve a spot in raid, the answer is yes, assuming we're talking about Elysium content (MC and Ony), you can actually clear all even with a full hybrid class raid (Of course will take far away more times), if you talk about optimization and wanna clear the content in 20 mins with an elitist raid, first of all you should play horde and take as a dps only Rank 14 warrior and rogue and give them Windfury.
Any other normal or even more dedicated guild/raid can always have a spot for a good ret, and as already someone say, if you wipe at MC, I'm 100% sure is not because you bringed a ret in raid.
For the math part about ret dps there are plenty of posts you can check by yourself (useless I write here all again), and everyone can confirm that ret can stay top 10 dps (thx to the low dedication of other classes players, like no consumables, often afk/autoshot etc etc.)
So in conclusion, unless you have a full raid of a rank 14 war/rogue dedicated players, a good ret will be always welcome.