Yes my friend, white gives away lot's of tempi, however when black plays e5 it weakens the d6-pawn and the d5 is also controlled by white and thus can become a permanent outpost for the white pieces and later d-file can be pressures by heavy pieces.
I have watched many of Daniel King's video's on the subject:
https://www.youtube.com/results?search_query=daniel+king+kelashnikov
I hope you will find the video's useful.
5 Nb5 immediately attacks the hole at d6, threatening 6 Nd6+ and thus more or less forces 5...d6, which closes the diagonal of Bf8.
5 Nb5 immediately attacks the hole at d6, threatening 6 Nd6+ and thus more or less forces 5...d6, which closes the diagonal of Bf8.
It is also easier to get back into the game from a3, going to c2-e3 and back to d5. This also doesn’t block and potential sight lines you may want open for your pieces, which isn’t the case if your knight ends up on b3.
1) e4 c5 2) Nf3 Nc6 3) d4 cxd4 4) Nxd4 e5
a : 5) Nf3 Nf6 which forces a passive move like 6) Bd3 d5 6) Nc3 Bb4 and the natural move 7) Bc4 dosen't work because 7)...Nxe4 8) Qd5 Nd6 and for ex. 9) Nxe5 Qe7 10) o-o Qxe5 11) Qxe5+ Nxe5 12) Re1 Ndxc4
b : 5) Nb3 same kind of problem 5)...Nf6 6) Nc3 Bb4
c : 5) Nf5 d5 annoys
d : 5) Nxc6 bxc6 in short we will play an equal chance position
e : Therefore by elimination 5) Nb5 is the best because it gives the most chance of playing in an advantageous position and White can also play "Maroczy Blind" after 5)...d6 by 6) c4
In this fairly common line in the Sicilian, one of the moves I've seen people play is 5. Nb5. I'm curious though, why Nb5? What makes the Nd4-b5-a3-c2 manuever worth it?