Why not WordPress
WordPress is popular — and full of compromises
WordPress is widespread because getting started is easy. You pay the price of that ease in operation — often only when it's too late.
Plugin chaos
Functions come via plugins from many different providers. Each is its own building site, and one update can cripple another — or the whole site. You depend on foreign developers maintaining their part.
Constant maintenance
Plugins, themes and the core must be updated constantly, also for security reasons. Neglect it and you risk holes; do it and you risk an update breaking something. Both cost time or money.
The logo breaks the layout
The classic: you upload an image or logo, and suddenly everything shifts because the theme expects different dimensions. In a template you fight against presets you don't control.
Speed & security
Many plugins mean a lot of ballast (slower) and many possible gateways (less secure). A large share of hacked websites run on outdated WordPress plugins.
In short
WordPress is a page builder with follow-up costs. Programmed code is the investment in peace of mind — more effort at the start, far less trouble over the years.