You are clearly underestimating the compatibility & accessibility challenges of reinventing the form submission code of a web browser from first principles.
Believing you can do so and not fuck it up is sheer hubris, not to mention, wrong. Doing so because you don't like the browser edge cases, is how websites end up suffering from even more edge cases, and harks back to the bad old days of "Sorry your browser is not supported".
Financial institutions are amongst the worst offenders - ironic since pulling this kind of naïve stunt vastly increases the attack surface. I've been in a position to redesign financial institution systems and rewrite their technology policies, and when doing so this kind of off-standard NIH crap is something I seek to stamp out.
Want to submit a form? Use a damn form, with a plain old submit button, and rely on the standard behaviour. Want to put some UI polish around it? Progressively enhance the standard behaviour.
What not to do: imagine you can write better UI<>protocol interaction code than that already in Chromium and Webkit, or hope to infer and reimplement the behaviours of any more specialised user-agents.
What you said. Most of what you said is common anti patterns. The reason is web technologies are built around a few set of standards that are designed for extension, such as the DOM and WCAG. Fearing those standards for a small set of static principles is common but that doesn’t make it smart. That’s why this technology space is so hostile to originality. You mentioned NIH but the more common problem is: https://en.m.wikipedia.org/wiki/Invented_here
Stop being so afraid and hostile. Embrace how these technologies work and more easily achieve accessibility with less effort. If you are waiting for some tool, NPM package, or framework to do it for you it’s not going to happen.
Abusing standards with shoddy inner-platform reimplementations doesn’t make someone an innovator, it makes them as much a fool as the cargo-cult of the NPM ecosystem.
So you think it's safer to rely on every engineer adding that (and the other facilities provided by web browsers by default when using native elements) to every input field in a form, than relying on them not doing weird things with that one form tag?
