Interesting post and I think it is very timely. I have tried using WordPress as a headless CMS for some time now. It mostly works.... but when it doesn't, it can be outright frustrating. This is why I have turned pessimistic about Wordpress' future recently.

I seriously believe the future of the web is in headless CMS'. But the more I work in the space, it is clear that Wordpress needs to be forked and optimized as a true headless CMS before it can be reliably used as one. There are a million different headless CMS products out there right now that I have been testing and have really fallen in love with these products. Sanity.io is a great one for a hosted option, as is DatoCMS. I think that Directus (which I have used on several projects now) is the closest alternative to Wordpress because it is free and self-hosted. I have been testing out Twill (twill.io) personally recently because it offers a block-based editor similar to Wordpress' new Gutenberg editor. That project works great headless or as an actual backend (built in laravel) and it also a self-hosted open source alternative.

These products are built from the ground up to accommodate different data models and to be managed headless. As a developer, I find it to be less stressful and much faster to use these products over trying to make WordPress work for a specific project and add all these bloated plugins. Wordpress is slow compared to what most Headless CMS' offer. And as noted in this article, it is clear that the team building WordPress are not architecting it to work as a Headless CMS.