In the end, both ways lead to the same result. Whether it's an inline error or maybe a bubble with feedback, the user gets to know why he can't proceed (which adheres to visibility of system status).
The point about disabled elements never having an action is understandable, but strictly clinging to this rule is not really of service to the user. If he could have a better UX with your product for the small price of not adhering to a rule 100%, I'd say it's worth it. You're not completely breaking it anyway, just slightly deviating from it.
With that being said, I personally think giving this feedback this way could be considered more modern or "cooler". So, especially if you're targeting a younger audience, I'd say it would be an improvement.
One drawback here can be that some users, who are very accustomed to the "old ways", could potentially find this unexpected and thus annoying. But that seems like a rather small chance.
Also another thing to consider: Users with visual impairment. Their screenreaders can catch inline error messages just fine (as far as I know), but a speech bubble might be tricky. At the very least, it should then simply grab system focus upon appearing.
Something like this seems to be a good way of doing it:
You can either show it on click of the button or have a smaller (?) button placed on top of it, which in turn doesn't break the disabled button rule anymore.