Benzene and proton in 1H NMR

The chemical shift in benzene is around $$\pu{7.27 ppm}$$, which is lower than, for example, aldehydes. However, the magnetic field due to the pi electrons are in line with the applied magnetic field $$B_0$$, resulting in $$B_{eff}>B_0$$. Whereas in aldehydes, the hydrogen is simply "less shielded". So shouldn't the $$\ce H$$ atoms in benzene (or alkynes etc.) have even greater chemical shifts than species that are deshielded "normally" through electron withdrawing substituents?

Also, somewhat of a side question: What kind of chemical shift would we see for a proton ($$\ce{H+}$$) in a proton NMR, since it is completely deshielded? Could this theoretically be measured?

(Following the previous logic, shouldn't benzene have a higher chemical shift than a naked proton?)