I mean, you're not wrong. That's the whole point behind a specialized workforce. The whole point to modern society is individuals focus on something and do it, really, really well. We then suffer doing other stuff competently. Other than the occasional hobby gardener, how many tech engineers know how to maintain a vegetable garden? I've asked this to a few people before. They just imagine it's as simple as throwing seeds in the ground, making sure there's water and waiting. Growing food on a decent scale, like feeding just yourself, takes a lot more. Knowing how and when to fertilize soil. How much sunlight. How much water. Seasonal timing for maximum yield. Recognizing disease and ailments. And it goes on. But we're a society where not everyone has to farm. That's both good and bad. Same goes with building homes, bridges, maintaining a water supply, electricity, preserving food, curing disease, etc.
But the drawback to that system, it's easier to wipe out a small population and start to handicap that society. Thus, you do have a "type of army" of structural engineers that build and help maintain bridges. If they're gone, there are problems.
I do have one... discussion point(?) I'd like to bring up. I constantly see and hear that liberal arts and what not is supposed to teach critical thinking. How does it do so more than engineering? Engineering especially forces you not to just think of the immediate solution, but long term both in terms of wear/tear, environment factors, attack vectors and future proofing against obsolescence. Yet, I'm told, rather often by other people that a liberal arts major can do this better than an engineer. Look, I'm a sub-par engineer and programmer. I say this often and will never hide it. But I've yet to meet someone with a liberal arts or literary degree that can do analysis and solution strategies on complex, real world problems anywhere close to me. Sure, I get hung up on theoretical problems. Really badly too. But when it comes to the real world, I've never met a non-engineer who can step forward on a, again, real world problem.