With screenplays, and most other kinds of scripts, dialog is king.
Yes, there’s a lot of other kinds of writing that goes into a good script. You describe what happens, you describe the settings, and you can give notes on how the words are spoken. But a good script writer tries to do as much with dialog as possible, and I think one of the reasons is, dialog is the only words in the script that (might) reach the final audience more or less directly. Of course, the director and the actor have their opportunities to tweak the dialog, put their own spin on it, but that’s a fairly minor change.
Everything else you write for your script, the audience is not going to have the faintest clue of the actual words you used. The director and cast and crew are going to read them, (you hope,) and use those words to guide the job that they do, and the audience is going to see the result of that, or hear it in ways other than words, (such as tone of voice, music, sound effects, etcetera.) But I think overall, those things can’t carry the narrative of a movie, or TV show or radio play, as well as the dialog does.
Many novelists or short story writers trying Script Frenzy as script writing newcomers find that writing script sharpens skills with dialog that they can take back to other kinds of writing. I certainly did.
If you’re a writer, then do you consider dialog a strong suit or a weakness?