Thanks for giving me a way to clear this up without the endless reinterpretation loop while also answering this. This becomes a severe problem in 5e once the GM wants or needs to step away from 5e's no magic items assumptions. There's no question that 5e's PC:Monster math assumptions of 5e are designed so that magic items are "always a boon"*, that causes a lot of problems still being discussed If the campaign is expected to last beyond a short one shot or something & the GM wants to use magic items for things like player/pc incentive to adventure take risks narrowing PC: PC CharOp disparity & so on they need rules to support the GM there once again. Now with 5e's "always a boon" design it will quickly require the GM to start making changes because the system provides no room for that use a second or third time without the GM reworking numbers somewhere to offset gains.Why are you assuming this is a problem, if I may ask?
Have you ever considered this might be much less of a problem in 5E than in, say 3E?
The first set of those changes will be to monsters & potentially areas like the DC ladder. The second set comes when the gm realizes that the players act logically & start minmaxing stacking into an arms race that the GM has no hope of countering long term without insane mudflation or putting in some form of limitation capable of forcing old items out like body slot conflicts.
Both 3.x & 5e have a section that covers that second goal, but they are wildly different. I quoted the 3.x one in 312 & 5e's in 275. The big difference between the two RAW is that one is written to support the GM where they most need the rule to support them while the other is written to get in the GM's way while providing no useful support even as it encourages players to engage in an endless debate over minced words like 302 & 309.
The problem resulting from that difference in support from the rules is that the 3.x version's low bar to say no to a player required the player to proactively make a good case for why they feel they deserve this exception before the GM ends that hopeful effort simply by pointing at the rule & the ease of forcing the GM to shoulder a high burden of explaining why the hopeful reinterpretation of "common sense" and any stray halfquoted utterance from the GM do not create an exception for the items in question in a rule intended to limit scenarios like a player wanting to do that very thing.
*Wotc has said they aren't required many times & xge136 literally says it.