Apple Keynote is the third of the big three Apple productivity apps. Apple Numbers I use all the time mostly for tracking things in various games I play and sometimes like a real spreadsheet with calculations. Apple Pages I use sometimes especially for stuff I want to print -- even for email if I don't write in Apple Mail I'll write it in TextWrangler and copy/paste.

I have created a slide show or two for work and done a presentation without any fancy transitions. I've used Keynote more as a diagramming/drawing to do sequence diagrams and flowcharts. But Keynote is neither a good Draw or Paint app and for publishing you are freezing the page as a JPEG or GIF and if you want to modify you have to go back to the original document. Nowadays I see the convenience of draw.io or similar where you can publish a drawing on the web and if you want to modify click edit which goes to draw.io, make your changes and save and the drawing is updated on your site.

Keynote is designed for slide show presentations which I rarely need. I've tried using it as Draw app which it is ok as (and better than using Pages/Numbers draw capabilities). I forgot Apple Freeform now exists so I should try it as a draw app even if I'm not doing a collaboration. Overall though I like Keynote when I've used it but imho not the best choice to fill out the basic trinity of Apple apps.