I won't dislike you. I consider a dislike an inferior alternative to a reasoned rebuttal. Herewith the rebuttal.
One bottom-line reason for SBS not using Improbable's services was to benefit players' bottom lines, that is, save us money. The relatively high fees that Improbable would need to charge would be passed on to us, through increases in the price of sparks and souls most likely. Another major reason was that Improbable decided to stop supporting the interface for the language that SBS uses. The language was chosen for specific developmental reasons, probably speed and ease of use. Changing away from that would have been expensive and would have increased costs and delayed development of the game. The current pre-alpha friends-and-family would have been delayed, and from that everything down the line would have been delayed.
Much, perhaps most, of the performance that Improbable is able to obtain relies upon Amazon Cloud Services. AMS is available to anyone at similar terms to what Improbable has. If I read my tea leaves correctly, SBS intends to use AMS. The reason I believe that is because the ping calculator actually tests latency to AMS portals. So, my informed guess is that SBS was confident that it could functionally duplicate the Improbable services that it intends to use for less net cost than the fees for those services would cost down the line, and was also confident that it could do so with less net loss of time than it would take to switch development languages.