I think there is also an efficiency question; fiddling around with any new technology takes time. I think most people might honestly just consider it too complicated after the first or second time reconfiguring, while seeing that using the site is still possible without...

In my case I was also a little surprised at how sometimes my linked wallet would get used for zapping, despite my account in the site having more than enough CCs and zaps accumulated from rewards... however it was a small amount and overall my net stacking and zapping even out.