Popular monolithic CMSs like WordPress, Drupal, and Joomla can be complicated to set up for each site, complex to run, and need to be managed and regularly updated to continue serving the site. And while they allow nontechnical content editors to edit site content and build new pages, they do so at the expense of making custom development significantly more complicated.
Headless CMSs may be more suited to custom development since they're designed to work with a Static Site Generator (e.g. Hugo) or meta-framework (e.g. NextJS), but typically at the expense of ease of content editing (since the system is decoupled from the rendering layer).
Headless CMSs need to be set up to work with a framework or SSG, meaning there's a lot more work involved to hook it up and integrate components, as well as setting up the other parts of the website (component library, prebuilt components, connecting to a web host or Github).
Using a framework also forces developers to do a lot of up front work to connect the disparate tools that help build websites, including a component library, prebuilt components, connecting to a web host or Github. All of these concerns cause a huge learning curve and up front work when setting up new websites.
With Primo you can create a new site with a click and easily manage tens or hundreds of websites from the same place without having to worry about maintenance or security, and update your site content with ease, whether you're technical or not. There's a growing library of professional components that can be used on any of your sites & adapt to its theme (using CSS variables). Custom development becomes 10 times easier because you can do it right from primo's component-driven development environment. Primo sites are built with Svelte, so components have rich interactivity with the simplest and most approachable code possible.