This is the consequence of a more general issue. It’s one of those sketchy Blender “paradigms” that they never want to change. This one is that most tools should be mesh element mode inspecific. This means that any tool should work from any mode. In reality, they are already breaking their own paradigm on multiple places, but they still push it in other place.
So they want you to be able to do edge bevels from face mode without having to switch to edge mode first, or to do vertex bevel from edge mode without having to switch to vertex mode first. The problem is that theory is often far away from practice, and in practice, imho, having two separate modes for Bevel tool is a worse and less intuitive solution than simply having one bevel tool which behaves differently based on the mesh element mode you are in.
The latter, imho better solution would also allow us to have bevel behavior for faces, where it could do what inset combined with “depth” parameter adjustment currently does. If we were to stay with the paradigm though, we’d now have even third mode for bevel tool “faces only”… That’d be crazy