agreed. i bet even Mozart would have difficulties positioning his fingers like this ;-)
Of course you could also assign another shortcut to this with BetterTouchTool or something.
In what way is a middle click dependent on the OS? And in what way is moving your hand away from the keyboard to click a mouse better than simply hitting a key combo?
The OS does decide what to do upon middle-click. In X11 (which handles input events and actions on most desktop Linuxes), middle-click pastes text selection.
Shift+Insert is the keyboad equivalent of middle-click, BTW. Apple (or the ecosystem) doesn't have a monopoly on keyboard shortcuts; in fact, it has been my experience that Apple UIs focus on touchpad usage too much, to the point of completely ignoring and skipping keyboard shortcut support.