Block themes promised the end of functions.php, the death of page builders, and a future where every editor was a designer. After 18 months running them in production alongside classic themes, here is the honest no-hype comparison.
Where block themes won
- Template editing in the admin. Editing the footer or 404 page in the Site Editor without touching code is real and works. Designers love this.
- Global styles. One JSON file (
theme.json) controls colours, typography, spacing across the whole site. Changes feel atomic and predictable. - Asset weight. Block themes ship less CSS by default. Lighthouse scores nudge up.
Where classic themes still win
- Deep customisation. If your design has bespoke layouts, custom post type templates, or specific hook integrations, classic theme files are still faster to write and easier to debug.
- Ecosystem. The plugins and theme add-ons you have used for ten years almost all still target classic patterns. Block-theme integrations are catching up but lag.
- Client comfort. Clients trained on Elementor or Divi do not necessarily benefit from the Site Editor. Some find the block paradigm slower.
The honest middle
Most production sites we manage now are hybrid: a block theme for the chrome (header, footer, post templates, 404, search) and a classic-style child theme for the bespoke template parts. This is not a fence-sit; it is a load-balance. The block side gets the editing convenience, the classic side handles the cases that genuinely need PHP.
Migration is the gotcha
Moving an established site from classic to block is rarely worth it. The migration eats weeks, breaks integrations, and the visible benefit to the client is small. New builds are a different story — start with block, fall back to classic templates where you need them.
The short version
Block themes are now the default we reach for on new builds. Classic themes are not dead — they are the right tool for sites that need deep custom work and for established sites where migration is more risk than benefit. The “block themes are the future” framing was true; the “classic themes are obsolete” framing was not.