Fair enough. Like I said earlier, I had just had enough and was/am incredibly tired of having to deal with it over and over and over again. Years of it. So, I perhaps over corrected to some degree and simply banned all the core caster classes. It's not like the game doesn't function. We still have the half-casters which pretty much cover most needs anyway. And NPC's can still be from the banned classes, so, if you need to teleport somewhere for some reason, you can go find an NPC who can cast it for you.
I just no longer have to deal with it on a session by session basis.
And, in the interests of clarity, this Phandelver campaign is supposed to be a fairly quick side campaign until work stops beating me about the head and shoulders and I can go back to my regularly scheduled campaign. I called it a palette cleanser in my elevator pitch to the players. The fact that two players simply bowed out and told me to give them a call when I start back to my Spelljammer campaign has somewhat taken me a bit aback. They are really enthusiastic about using the full casters and have zero interest in playing anything else. Which... honestly... is kinda making me feel a lot less enthusiastic about going back to my regularly scheduled campaign.
We'll see how I feel in a couple of months.