[Cthulhu_]

It's because customizing a Wordpress theme is a daunting task at first, especially if you try and use the builtin editor instead of taking a theme and stripping it down. WP's page layout and templating is... Different. Which is why it's turned into its own specialism / industry.

[lolinder]

Again, though, we're talking about a web dev who had previously been managing their own hand-rolled blogging solution.

Something like sticky menus should be trivial for any web dev: find the menu you want to make sticky in the web inspector. Modify the styles inline until you make it work. Grep the theme for the selector that you modified. Copy your modifications.

[gifmenger]

Yet using it as a headless CMS allows any dev to just circumvent it's theming dialect altogether.

I think that really illustrates Wordpress' versatility.