For non intensive apps, no argument. But I multitasked like dickens on my iPad Mini 4 too. I have a hard time multitasking on the 2018, some of which I pinpoint on memory due to freezes, page reloads and slower responses.
On the 2018: I am noticing an increased amount of bottlenecking in Procreate when I try to do shading and other things. Also Safari is a mess (Nothing new there). As apps grow, stuff happens, I get that. I get that my workflow is not yours too. Eventually, I will move on and this 2018 will be fine for mom.
While I won’t be surprised if the rumored Mini just a cheaper mini 4, I would be delighted if it’s closer to the Pro. And I’d pay the introductory Pro price ($649) to get a Mini with the specs I desire.