Steps to Reproduce:
The result is that the open editors pane does not disappear from the explorer view. It remains visible showing only one entry - the currently focused tab instead. Switching a tab changes this single entry to the newly focused tab. Setting the "explorer.openEditors.visible" to 9 or something works as intended, showing the opened documents.
@isidorn can you look?
Can not repro this both on win10 and os x.
Do you still see the behavior with "workbench.showEditorTabs": false?
If you reproduce it regularly can you please attach a short gif / or at least a screenshot

There you go. You can also see all my settings on the screenshot. Btw., I notice my explorer view looks whole lot differently than yours.

ow ... and yes - it is all the same with "workbench.showEditorTabs": false. Also here I demonstrate it with split view, but it is all the same without splits.
oookay ... found the difference between mine and yours - you have a folder opened. If I open a folder - all looks just as yours and ok, when I close the folder - then the above happens.
Yes - this is as designed - you have a no workspace view and in that case we always show the open editors view.
As soon as you open a folder for your workspace that setting will be respected.
If more users find this confusing I can reopen this issue and always respect that setting even in a no folder workspace.
ow ... clear ... though a bit confusing indeed.
+1 to revisit this issue - totally expected the pane to disappear after following the instructions in the comments...
I'm curious why the pane remains there if no folder is open? @isidorn mentioned that it's designed this way... would love to understand why.
If nothing else, the comment in the JSON should explain when this setting will be respected...
IMO this should be looked at again. I set "explorer.openEditors.visible": 0 and in the "no folder mode" the list has the height of 1 item, even when I add open 10. So for me it is a bit confusing on one hand and not a helpful "feature" on the other hand.
My expectation would be that the pane ist always hidden when i set 0.
Most helpful comment
+1 to revisit this issue - totally expected the pane to disappear after following the instructions in the comments...
I'm curious why the pane remains there if no folder is open? @isidorn mentioned that it's designed this way... would love to understand why.
If nothing else, the comment in the JSON should explain when this setting will be respected...