Bb5+ in the Hyperaccelerated Dragon

I was looking at the Hyperaccelerated Dragon, and found that after 1. e4 c5 2. Nf3 g6 3. c3 Bg7 4. d4 cxd4 5. cxd4 d5 6. e5 Bg4 (see study), the most common continuation in the master's database is 7. Bb5+ Nc6 8. Bxc6+. This surprised me, because white gives us the bishop pair, and his good bishop (given that white's pawns in the center are on dark squares). The engine, however, agrees that this line is best. Does anyone know the theoretical justification for this exchange? Why should this be preferred to something like 7. Be2?

I play this with both sides. From my experience, after Be2 the D4 pawn is a nice target for black and the bishop on f3 doesn't do much. Black can play for f6 at some point weakening D4 further. After Bb5 and Bx the C6 pawn will always be weak and C5 is hard to achieve for black.

The Alapin is so interesting. If I played 1.e4, that's the variation I would spend my time learning... But I don't play 1.e4, because there's so much stuff you have to know.

Black's bishop pair doesn't look terribly impressive at the moment.