Four reasons that hold up, from hosting several thousand WordPress sites.
The site is files and a database you can download and move to any host. Nothing about it depends on us continuing to exist, which is not true of most drag-and-drop builders.
Changing a price, adding a staff member or publishing a post does not need a developer. That is the single biggest reason businesses stay on it.
Bookings, stores, memberships, multilingual sites and invoicing all exist as mature plugins. You are rarely the first person to need something.
If whoever built your site disappears, the next person already knows WordPress. A bespoke framework makes that handover expensive.
The honest half. Two of these are why businesses leave it.
Core, themes and every plugin ship security fixes. An unmaintained WordPress site is the most common way a small business gets hacked, and the clean-up costs far more than the maintenance.
Each plugin is somebody else's code running on your page load. Sites that feel slow usually have twenty of them doing the work of five.
If you need a single page that never changes, WordPress is more machinery than the job needs. A builder or a static page is cheaper to run.
WordPress is database-driven, so it is more sensitive to the server than a static site. Most "WordPress is slow" complaints are hosting complaints.
Plans, prices and the practical pages behind the advice above.