Is this because WYSIWIGs are inherently hard to make, or because of browser-specific challenges? Was this due to compatibility issues between browsers? I've w

Is this because WYSIWIGs are inherently hard to make, or because of browser-specific challenges? Was this due to compatibility issues between browsers? I've written my own native Windows WYSIWIG editor and a fair amount of web UI, and was thinking of rolling my own web-based editor.