Exactly! That's an excellent argument for using PE and writing device-agnostic code!
Taking partial quotes and out of context to boot doesn't make you cute 
You said it was an intranet? You'd know every user and what devices/browsers they're using. That's not the case for public services even if they're behind a login.
I did, as an example. And I definitely know that all intranets are not that closed - so that you'd know every user and device. And you didn't answer the question - I'm asking what you consider part of the web, and what you consider to be needing to follow your principles?
Great! Let's use pointer events: it has good cross-browser support. Except for Safari. But who cares - that's only used by 5% of the desktop market and Apple should "keep with the times"!
The point is that PE allows you to use modern technologies without waiting for others to catch up. Why is that a problem?
It's not a problem at all, in some cases! Maybe even most cases, I don't know; but in every case I believe that the developers/owners have the right, and the freedom, to do whatever is correct for their application. It doesn't really matter what you think, or their users think, even - if their users dislike the service, then they'll go elsewhere
I personally might steer away from things that 5% of the market can't use; Jane Doe developer down the road might disagree, and think that that 5% wasn't relevant to her app. Who am I to judge her for that decision? She knows her clients, app, and stats better than I do!
If you develop for a subset of browsers, only people with those browsers will use your site. Those who can't use it will disappear from your audience and statistics. They rarely complain - they just go elsewhere.
And if that's not a problem for you, then fine! If it is... then do something about it. I don't see why this is a contentious point.
PE allows you to develop for the web - not browsers. Developing for browsers is a bad idea. Ask IE6.
IE6? Is that an argument of some kind?
https://www.modern.ie/en-us/ie6countdown 
PE is a fine idea sometimes, especially when dealing with static, informational content; and maybe some of its ideals can be employed in more complex applications, but as a standard across all of them? It just doesn't make the same sense to me as it does to you.