You mentioned each person had 10 magic rings though. That is abnormal. Also, the 2024 DMG specifically says:
Are Magic Items Necessary?
The D&D game assumes that magic items appear sporadically and that they are a boon unless an item bears a curse. Characters and monsters are built to face each other without the help of magic items, which means that having a magic item makes a character more powerful or versatile than a generic character of the same level. As DM, you never have to worry about awarding magic items just so the characters can keep up with the campaign’s threats. Magic items are truly prizes—desirable but not necessary.
So if characters and monsters are built to face each other without magic items, and the PCs have a bunch of magic items, then the DM must account for that. I don't run published adventures, but if they are just using stock monsters then the DM absolutely needs to account for the PC magic items.
To me, these things:
1. Seems at odds with one-another: "game is balanced against zero magic items, but also here's a tracker as a guideline for how many magic items you should have.." that says to me that the game is not balanced. Is that a problem? Not necessarily, but it can throw the GM for a loop... And exhaust the setting of powerful creatures trying to challenge them (PCs punching way above their weight class is my personal issue with 5e).
2. Given that the balance is made without magic items, but adventures and the chart provide expectations for plenty of magic items... This is probably something to have been addressed with the 2024 system update? Start designing stuff assuming some amount of magic items. That ship has long sailed ofc.