You seem to imply that there is a path from beginner=non-coder to advanced=coder, and no that’s not the case.
You’d be surprised at how many professional sites are done in Sparkle, in fact many commercial songs, feature movies, highway billboards are also done in WYSIWYG apps
The Sparkle user interface appears simple, that’s by design. The implications of clicking a checkbox are not simple, we spent thousands of hours on ensuring the resulting code works on as many browsers as possible or gracefully degrades when it doesn’t, on making sure the PHP code Sparkle generates works across server versions and configurations, on keeping that pagespeed score up every time they raise the bar, and so on.
In fact I posit that the real amateurs are the “fake it till you make it" people who never build a properly engineered website, again in terms of proper functionality, performance, privacy compliance, security and accessibility.
Yes Sparkle doesn’t do everything, but the fix is not to add the ability to add code, it’s to create visual tools to allow more people to create their professional site, rather than restrict who can be defined as professional.
In fact the left brain/right brain dichotomy suggests people who are more skilled at creating great designs are going to be less proficient with the symbolic nature and detail oriented busywork of code. So who’s the real design professional there?
I guess the market will decide whether competing tools are better than Sparkle, right? A couple or three of the ones you mention are already dead by the way.