It might seem vague or rudimentary but it is a common occurrence in business. We can take the conversation deeper now if we'd like, If you don't feel the need to expand on the idea yourself or feel the poster didn't set you up to do so, that is understandable.
I think it's interesting to talk about how "act your size" can also be wrong. Sometimes fake-it-til-you-make-it is the goal. Contextually you should hold both ideas to be true and apply them appropriately.
Maybe you just thought the original post is a vague platitude and you don't want to give them the satisfaction but maybe we can share some of what we've experienced.
One thing I always think about is hiring generalists vs struggling to maintain departments you can't sustain. I understand businesses think this way, so it influences how I think about applying to roles. I'm currently in a generalist role and when searching I always look for smaller businesses because I find my impact is higher, and repetitive work is my greatest fear.