Personally, I routinely use Photoshop.
I have CC 2018, but have not even downloaded Lightroom.
I think it's a bit more than you say.
Light room is a photo management tool, as well as having a sub-set of photoshop's editing facilties.
Also, changes in Photoshop are pretty much permanent, whereas the Lightroom keeps the original when you edit it and automatically sales the changes on top of the original, so that you can easily undo.
In short, Lightroom is a bit safer and a bit less of a sledgehammer to crack a nut, of you only want to do light editing, and don't need to get down to each individual pixel.
See here:
http://blog.creativelive.com/use-photoshop-lightroom/