I had the complete opposite problem when I went back to Maya in the last weeks, I was not able to delete what I wanted and needed to relearn how Maya internally works and ran into issues where I was not able to delete certain empty edges etc till I attached them to Faces and thus was able to delete the face with the edge.
It is quite important for new Blender users in general (not only those coming from maya) to realize the many mistakes they can do like extruding something pressing esc not moving the mesh and having created duplicates.
“Remove Doubles” is a command my students use a lot at the beginning because they overlook this accidental geometry creation.
Yep, because if you have at least one polygon, it is an object. Thus the object must be deleted in Object mode. More than 1 polygon can be deleted since the object still exists with at least 1 remaining polygon, but them moment you want to get rid of that last polygon is technically the moment you want to remove the object all together. Thus object mode.
I just needed to get back to how Maya thinks or treats geometry. Coming from Blender this can be very different. And while I used Maya around 2004-2006 I must have gotten so used to the way Blender works that I for got about Maya’s rules.
The other most annoying this I experienced with Blender but that might be more do how others saved the mesh is when you get OBJs imported and you have crazy overlapping faces and there is no easy to to clean this up besides trashing and rebuilding parts.