Are visual website builders just selling theme customization?

It becomes a must to have pre-built templates for these apps. Their demos only show "almost-done" kind of example. Imagine comparing each of these with criteria of starting from blank page, it would show more awkward moment trying to arrange details of layout on deep level elements.

There is new kind of builder that's trying to free users from limitation previous generation used to have. That is to render layout from code and generate code (two-way). But it becomes YesCode (Low Code is not enough for 100% customizable and extensible), and also ties to particular paradigm of how their code do styling because the UI needs to understand and be able to render it as well as to generate the code in some style (can it generate styled-component, tailwind, etc?). Therefore, they end up doing a lot of pre-built components, let users drag and drop and customize, so YesCode is now closed to just selling widgets library since composing part is already easy at this point, probably easier than using the gui one.

Apparently, these site builders serve well, so there is huge market. If I asked "is the market saturated" 5 years ago, the answer was probably yes, and proven wrong today. But I wonder if this time the market really is saturated, how could them be better than this, they seem to already reach both end of <-convenience--------flexibility-> spectrum.