They are arguably essentially buying revenue to help their bottom line. Salesforce hopes to add $350-400M to their FY20 revenue
That's a pretty steep price to pay for a single-digit % increase in revenue. I view this more as filling a strategic hole. BI & Analytics from Salesforce are awful.
I don't know much about company account structures and finance dynamics, but that doesn't sound like much compared to the $15.7bn price?
Can you elaborate on the advantages of Periscope? I've used Tableau, but not Periscope. Browsing their site & marketing materials, it's not really clear to me how they're much different from Tableau.