And one more thought
@dave2008.
First, I'm really sorry. I was incredibly rude. Thank you for your suggestions. They are actually very good suggestions and they most certainly would work.
However, in the context of this thread, I'm not sure that they are particularly "easy". After all, if I was to run a low magic D&D game again, I would use 4e, Martial only. PHB only actually. Right there, I've got four complete classes - ranger, fighter, rogue, warlord, which cover all the roles except controller, which, frankly, isn't really needed anyway. A five person party of 2 fighters, a ranger, rogue and warlord would work perfectly fine.
That gives me all the tactical depth I want in combat. I don't need any supplements and I know that it will function perfectly fine. Heck, if I wanted to be really good, I could simply add the Inherent Bonuses rule and I'm done. To me, that's about as simple as it comes.
Or, rather, I find that a far more simple solution than cherry pick material from four different supplements which still leaves me without the tactical depth in combat that I want - even with feats, you cannot make an area attack for example with a non-magic character, so my "sweep sand into their eyes to blind them still doesn't work in 5e without making up a ruling at the time - and quite possibly has all sorts of knock on issues like healing and whatnot.
So, yeah, if someone asked, "How can I do low magic in my 5e game?" my first response is always going to be, "Don't. It really doesn't work worth a damn. 5e is set up to be an extremely high magic game with spells and spell effects being used every single round and in every single combat. You'd be far better to use 4e instead."
I'm still not seeing how that is rude or offensive.