True to an extend. But that is not the be all end all for playing. Some people do play for fun.
Besides, if you follow the mantra of what you said. Gear plays no part it. If a piece of improves a player character by 10% and the next challenge is made harder by 10%, then the net balance between the player toon and the challenge remains the same. So what has the gear done besides gating the content by requiring player to have beaten the previous content? The same effect can be achieved by other means.
I think you are being too general with that assertion. Unless you know them all. Yes. Some players are complaining. This not new. This has happened before. This is happening now. And it will happen again regardless what changes Blizzard make.
Players from the entire spectrum of the player base will complain. There always will be. They however, do not necessary represent the entire player base. Afterall, if they are enjoying the game, they have nothing to complain about so we never hear from them.