Been saying this to my guildies all the time, especially the ones that come back and ask, "which class is best in raids right now?"
In 99% of the groups that you join, the class does not matter. So stop picking Fotm classes and stay on one you like and MASTER that class.
In MOST cases, a class that 'sims' bad at 95% of its potential is better than a good class at 85% of its potential. (Made up numbers, but you get the picture)
IF you're in such 1% group where classes matter, you are going to be changing classes often and will cater the composition depending on the fight. (For first kills, at least)
In that case, you are putting progression over your class preference.
For the rest of the players( the majority) the balance is close enough that if you are a good enough player, you will be able to do well. (Depending on fights, of course)
A few other things I've noticed in recent Blizzard statements:
* Blizzard doesn't generally make fine-tuning adjustments during a patch, because many players react negatively to change. They are especially afraid of "forcing" DPS classes to respec (like they sort of did for fire -> arcane in T14, because they didn't anticipate scorch weaving). So typically hotfix nerfs and buffs only come for the real outliers.
* They're more concerned with difficult fights than they are with easy fights. I think Ghostcrawler said he hates when players look at an average, because nobody cares who did the most DPS on easy fights like Stone Guard.
* They actively want some amount of imbalance on particular fights (or parts of fights), because it makes the game more interesting, as long as (a) it isn't too much, and (b) the class who shines in a certain situation isn't also top of the pack everywhere else. Elemental shaman can be the best against 3-5 clumped mobs if other classes get to do best on single-target or multi-dot fights.
Observationally, they also don't seem to care very much if a pure DPS class has one spec out of three that nobody uses.
Lore what you say in this video is absolutely fucking right and even a bit understated. Even in the top 200 guilds where I've been raiding for for the past 2 years there are people who underperform in their specs. Hell, I've seen guilds in the top 50 that just couldn't put out the numbers their classes could at fights like Ultraxion. My guild is a top 50 guild at the moment and while all of our DPSers are extremelly good players, only one of them really plays his class at 100% efficiency.
Basically, unless you are absolutely 100% perfect at playing the game (which is maybe 10 guilds in the world) you're better off blaming your failures on yourself rather than complaining about the balance.
Thing is, even at the top 0.3% of raiding, it usually comes down to executing the tactics right, switching to DPS the correct targets in time etc etc, rather than pure numbers on the DPS meter.