Enterprise applications are those that are built for, enable, and underpin enterprise sized concerns.

So for your financial department you want and enterprise application that owns, orchestrates, and audits the work of finance.

However most if not all business processes cannot exist solely within an enterprise application, so you want to give them "tools for application to the business process". That's probably more high-handed than it needs to be, but eh :D

So in this what I'm arguing is that MSFT here isn't trying to position Power Apps/Automate as a tool for developing enterprise applications, but rather high-grade capabilities (I'm remiss to say "enterprise grade" as people will then conflate that too) that allow the business to tie all ends of their business process together. The best way to do this is by giving everything outside of the enterprise application knowledge and reach to each other via API.

To your point, yes, this could require the business to build applications for their own processes, but these aren't enterprise applications, simply process specific applications.

Traditionally these were macro enabled Excel workbooks and Access apps that were squirrelled away deep in so many Network Drives, underpinning vital business process functions but wholly unknowable to leadership or those maintaining the enterprise application itself.