Couldn’t agree more with what Mark and John, both of whom are thoroughly knowledgeable about the possibilities and limitations of LR, yet also well-versed in PS.
My own personal experience has shown that LR is ideal for creating highly “polished” “straight” photographs, a super-up darkroom if that means anything to you; i.e. where photographers want to get the absolute most out of a scene as photographed. But you know this already. For many of us, LR is the ideal tool for this.
With PS, you can do all of this through ACR, but then have the added tools of an art studio to make radical and significant changes to an image with limitless “creativity” beyond what LR doesn i.e. to change your digital file from a photograph to more of a mixed-media creation.
For straight photographs (and I hesitate using that term as it carries some baggage with it, but I hope you know what I mean), some photographers use the curves, layers, sharpening and, perhaps most often, the healing tool, to, in effect, do the same thing as LR does, once you know the depth of possibilities with LR. Others find these tools in PS allow them to tweak the photograph more than they can do in LR.
In one sense, different horses for different courses.