The issue with a front-page.html template is that it does not respect the default "Your homepage displays: Your latest posts" setting in Settings > Reading.

It's true that in the classic era, themes (submitted to .org) did need to respect the Reading Settings, and yes it's possible that theme authors have become conditioned* into this way of thinking, but it can be super confusing for users when the homepage does not display the latest posts if this is what they expect.
Maybe the default to latest posts and the page_on_front and page_for_posts options should be removed/disregarded when a block theme is active?

*How can I be sure that what I am saying and my reluctance to include a front-page.html template is 100% my own thought or whether there is some conditioning at play here?? At this point how do I know the difference?

Recently another theme author asked my opinion on this very subject. My advice was basically the exact opposite to what you are saying in this article Justin, but over the past couple of weeks I have been giving it some thought and I'm not opposed to change my thinking if the legacy issues could be made less confusing.
There's also the issue of content directly in the template. Surely a template is a template and not itself the content?