tyrlaan
Explorer
Than you need to find a different system. D&D has always had that kind of campaign changing magic and always will. It shows it in different ways at different times in different versions, but any campaign that lasts a decent period of time is going to have that kind of change at some point and a long campaign will have several. It's one of the biggest reasons why most campaigns end around 10th-12th level. Take that away, and it's no longer D&D and people's acceptance of it will drop accordingly. Even 4E, which still had it, despite being far better masked, had to overcome the very real argument that for many, it did not feel like D&D. It's part of the system. You can mask it all you want, you can try to mitigate it all you want, but most people who play D&D at this point do so precisely because of that type of magic, and those who want to play low magic while using this system consistently have to fight not only the system, but the perceptions of most of their players as well. The idea of low magic simply does not fit well with a system where half of the classic party are full casters.
I don't think this has to be the case, but historical trends definitely agree with you.
I do however think that many people over the years have chosen to run a low magic game in D&D for better or worse, which means they had to tackle these issues. The missing ingredient to truly handle the power disparity without a boatload of houserules/class and spell redesign would be for D&D to have some sort of power "dial". So maybe there are three "settings", low, moderate, and high magic, and when you pick one it not only adjusts magic item rarity/power (which is where the magic level is typically tweaked), but also spells/classes and monsters/traps.
I by no means suggest this is an easy design space to romp through, but it could be done
