Hey Shawn, great article!
To answer your question, Nintendo was there for us before any other gaming company, or even in cases where they weren't there first, they were the first to leave a lasting impression on our impressionable, young minds. Think of all the Pokemon adventures we've gone over the years, or how many different times we've rescured the Princess from the clutches of Bowser, hopping from colourful level to colourful level while being lulled by the sweet soundtrack of our childhood. I distinctly remember the first time I ever played Super Mario 64, in a basement in California, I was completely blown away, right away.
I love that you mentioned Shigeru Miyamoto. Simply put, the man is a worldwide legend. But I feel you can't mention Miyamoto without also mentioning Koji Kondo, to me they are joined at the hip. Kondo like Miyamoto, is a legend, especially when I think back to how Mario and other Nintendo games would've been received without his infectious music, over the course of 35+ years. His music made a lot of the most popular Nintendo games, just completely come to life.
Nintendo's brand loyalty is no different than Apple's. Nintendo like Apple and Apple like Nintendo, both fundamentally and with great knowledge, have nearly perfected the critical importance of merging great hardware with even better software. You can't play Mario without Nintendo, you can't use iMessage without an iPhone. It's a genuis selling point, really. I solely bought a Switch solely so that I could play Super Mario Odyssey and Super Mario Maker 2. Both companies operate to the march of their own drums, not concerned with what their rivals are doing, instead creating industry shattering innovations in their respective, unique styles.
Nintendo hooked us in as kids and even as most of us have lived through our respective adulthoods, we've been unable to shake the nostalgia and staying power that Nintendo offers, an ability to embrace your inner child and to play games as they were meant to be played, for fun.