Maxperson
Morkus from Orkus
I guess items may make the difference between being able to complete 6 encounters and being able to complete 8 encounters before being utterly drained.
Most 5e groups don't fight 6-8 encounters per day so the somewhat increased resource attrition is not an issue. IME encounters are usually about "Will we win" or "will we win without anyone dying", and (probably due to bounded accuracy) magic items seem to make only a marginal difference. Whereas in high level 3e & 4e items (or inherent bonuses in 4e replacing items) are vital.
If the DM is not giving those 6-8 encounters a day, he will have to make what challenges he does use much more difficult in order to compensate. That means that if he reduced to 4 a day, you should be running out of resources by encounter 4, even with those magic items. Take away those magic items and encounter 4 will likely kill you given the increased difficulty.
If the DM has not increased the difficulty to compensate, then he might as well just be handing out free exp, because those fights will be so easy with or without the items that there is no point in wasting the time to "fight" them.