Sibling is right that video was the problem for me with that specific bit, but also: Text isn't necessarily a hard requirement, but the alternative is harder, in that then you need a tool chain that covers everything we do with code. That includes putting it in blog posts, emails, Slack in ways that are searchable, and can be decomposed into smaller bits, so images are insufficient.
It's possible for a visual programming system to work without it, but it will need to be accordingly a far bigger step up.
Consider searchability on e.g. Stack overflow for example. If people don't have a consistent, shared vocabulary, just lack of searchable exposure is likely to forever condemning it to a niche.
The context within which we build visual programming languages needs to change in order for it to stop being a niche. As you point out, the alternative is [much] harder [today]. But I think that VR, as an example, will be forced to solve a lot of difficult UX problems if VR is to progress beyond a niche. And once those problems have found satisfying solutions the context for building nice visual programming languages will likely also have improved significantly.
I don't see what VR has to do with this. You'd still need all the software you transfer this information via to support more complex data, and you'd still need a vocabulary to communicate about it. And if you have that, it doesn't need to be VR.
(EDIT: And specifically to the sentence you cut that out from: For it to appear in search results, and so be discoverable* it still needs to be in a form that search engines know how to index)
There's nothing technically preventing us from having all our software allowing the embedding of visual code elements that can be manipulated via components - the technology to do that is decades old.
The problem is a combination of social, inertia, and the chicken and egg problem of there not being any sufficiently compelling visual programming system creating a significant reason to push for this.
I don't want to discourage people from trying. By all means, try - I'd love to be proven wrong, and I think you might very well discover something useful or learn worthwhile lessons from trying to push the limits of this. There are just lots of pitfalls to address.
