can vouch on this, since originally I really prefer WYSIWYG UI (VB, C# winforms, wpf) over web early. However security-wise it's hard to enforce when using them, since they don't really operating using client-server by default, having your backend logic prone to be reverse engineered.

This doesn't happen in web apps, since backend logic stays on the server. Whipping a html UI over the already server-client architecture is easier. In addition with ease of deployment of application making web apps very favorable.