After the slippers of spider climbing initial argument we had another later in the campaign. I wanted to borrow another PCs ring of water walking to use with the slippers to walk up a waterfall and sneak into the bad guy lair. I thought I would be able to walk up the waterfall since the ring allowed one to walk across running water. His argument was that the water was flowing faster than my speed so I would not make any progress and later in the discussion, it was brought up that standing in a river would still push you downstream even though you were not touching it. I was thinking that not actually touching part meant that water would just flow under you.
I think it ended up with the point of the slippers needing to touch the wall and ceiling to stick to them and the ring not actually touching part meant they would not work together.
Again, it just strikes me as a DM who was fearful that the items they were giving out were suddenly too powerful and had to be contained, which just creates unnecessary uncertainty for the player.