This is an unsophisticated perspective. Have you seen how fast WhatsApp is growing? They could easily cross 1B users in a year. Daily actives are at 72%. They are insanely engaged.

The move is probably largely anti-competitive, but there are certainly inroads to drive additional facebook engagement, which further boosts revenues. It's expensive, but remember that FB is a 170B company.

Lets just hope that FB doesn't get too invasive with the product.