This does not solve the issue, if you enter a folder with RET (a slightly more obvious key than `a`), it still opens a new buffer for every directory. What you would have to do is to remap the key in dired's keymap. Which still doesn't solve the issue that it keeps the buffer open even though you close it with `q`, which requires some other fix.

Or: you can use a file manager that isn't made by crazy people, which is what I do. I say this as a loyal Emacs user: there are so many things in Emacs that are amazing (org-mode and magit are the two famous ones obviously, but a personal favorite is Emacs calc, which is just a work of art), but dired is not one of them.