Why THIS note is used over the V chord

This is why you often hear blues players add THIS specific note to the usual minor pentatonic, when playing over the V chord.

It’s just a very sweet note for this chord, and that’s because it’s part of the chord itself – it’s a chord tone; it’s part of the V chord triad.

BB King did it, SRV did it, Clapton does it, Hendrix did it – everyone and their dog does it, and now you know why.