No, it's not nonsense. Not in the slightest.
You all seem to assume that it will take the fastest player only months until he has maxed out every skill. But that's only the case if it's designed to be that way. That means you can design it so even the most dedicated player needs years to max out everything.
If you design it that way, in 5-10 years, without any additional update to the game(!), I'd estimate about 50% will have maxed out everything. If it's done right.
And with additional updates, which I, and surely you too, hope will come, there won't ever be someone who comes even close to maxing everything out. And thus there will always be a need for specialists and there will always be cooperation and trade.
That doesn't mean it's easy to find the right spot for the leveling difficulty but that's not the point here either.
Now when I look at the types of players I see 3 of them: The ones that want to skill evenly anyway, the ones that want to specialize anyway and the ones that don't know yet.
The first two don't matter because no matter the system they will do the same thing. The last one on the other hand is the one the system should be targeted at.
I think those in that third group are people like me. They would like to specialize because it's kind of fun but they don't want to sacrifice anything else because that's dumb.
(I can't see a reason why someone wouldn't want to specialize unless he has to sacrifice something. If you have a reason for that kind of behavior then please tell me.)
That means a system with caps would swing that group to spread out their skill points or make them invest them in a way so they can unlock the most things. Of course without specializing.
While a system without caps would swing them the other way to be more specialized because they don't have the fear on loosing out on something. Because eventually they could still unlock it, even though it's almost impossible to max out everything.
So the conclusion is, it doesn't hurt any of the social goals of the game at all if you don't have caps. It even helps them. Yet a system with caps would hurt the social goals of the game while not really helping them in anyway.
And as always if you have a counter argument, I'm happy to listen to it. I don't want to be right I want to find a solution/the truth.