There is no duplication problem)
During intensive/complex work the order of tools is constantly changing,
there is bevel after extrude after grab after scale (workflow-oriented approach),
not extrude after extrude after extrude after extrude (tool-oriented approach).
There are two types of tools systems.
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The button tools system is for beginners. It allow to users to get into 3d, to make them understand that there is “extruding” and “beveling” in 3d modeling through interface. Those tools are not designed for intense work, because it takes too much time to switch between them, and they forces using gui.
The button tools represents a tool-oriented approach. -
The shortcut tools system is for advanced users. It is used by people who already know the difference between beveling and extrusion, because they have used them thousands of times, and the only thing that interests them is their quick call without a gui and widgets.
Shortcut tools prioritize quick access to a mixed order of tools during an intensive workflow.
The shortcut tools represents workflow-oriented approach.
Previously there were only advanced system in Blender. It allow to work faster than in other software, but as a system it is not obvious for new users - basically, you have to be a 3dsmax user for decade to understand its benefits (there was time when 3dsmax was showing random hotkeys on a splash screen to make users learn them. The layout wasn’t good, but the idea of using hotkeys was nice).
So button tools system was presented in Blender to lower entry threshold, as well as industry standards hotkeys which are pretty much inconsistent, but was learned by lots of people since 2002.