I'm with you for the most part. Today, with modern browsers on almost all devices and relatively high memory, compute and bandwidth capabilities - for certain.

I'm with you for the most part. Today, with modern browsers on almost all devices and relatively high memory, compute and bandwidth capabilities - for certain. However I can't agree with this: > The UA header never had any business existing to begin with. The early mobile web, and devices that were just too low-powered and/or low-bandwidth to support even early CSS/JS-based capabilities detection absolutely depended on server-side rendering to serve them mobile-HTML friendly sites. Yeah, it was terrible, it was painful and insane to manage - but was necessary.