This is a good point, which I didn't get until your comment. I think they should surface this on that page, because it seems everyone is thinking this will be a big clash, but as you say, if someone shares a sentence, the likelihood is low.

To double check, does this means things like,

  https://www.spa/#!/path/to/view

Can become

  https://www.spa/#!/path/to/view&targetText=percent%20encoded

The only part I don't get about the likelihood and this extension is how it interacts with these kind of hash routes.

I haven't thought that much about the next part, but how do people feel about the following?

  web+text://https://www.spa/#!/route/to/view#targetText=percent%20encoded

or something. Rather than extending URLs vertically, extend horizontally into a different protocol the URI of which can encode the syntax elegantly.

I think that's more risky in that most browsers and many intermediate proxies or other traffic inspectors are likely to have special casing around http: (at least) and https: and for most traffic to be over http(s): and a tiny sliver over web+text: seems fraught with more peril than a (fairly small and intention-aligned) abuse of #fragments. Even mail agents, markdown processors, and other text-display applications often have special casing to turn http(s) URLs into touchable/clickable links.

Page authors are unlikely to use web+text: if it means cutting off old browsers from access.

Googles’s fragment solution should gracefully degrade to behaving like the normal link in other browsers (as long as there isn’t some fragment conflict) but creating a new pseudo protocol would have to be supported by each browser to even get to the site.

You could use two hashes like that and stick with http. I reckon browsers would cope, and you could strip the second one.

Well, if we're talking about intention, they were originally a browser feature allowing to scroll to a specific <a target=..>. They were invented before JS if I'm not mistaken, so the assumption was that the browser was handling it.

That is true of any URL, the user can decide to use it in ways you don't want. But that is also an intrinsic feature of the web. The best approach is to give users flexibility, but accept that websites may overide that behaviour.