Because bip47 sucks for senders while SP sucks for receivers. Encouraging the sender side probably results in more adoption.
Discussion
SP is super simple. I’ve used it on Cake wallet and it worked great. And the receiver I sent to was totally new to the crypto world as well
Quoting an article on BIP47:
> Complexity and User Experience: The need for a notification transaction and the management of payment codes can be complex for average users unfamiliar with advanced Bitcoin features.
> Cost Implications: The notification transaction necessary to establish a payment channel incurs blockchain fees, which could be a barrier in times of high network congestion.
That's why it worked well, because the receiver is "new to crypto". That's because, to receive SP, receivers need to scan every block and every transaction so that they can perform a computation to determine if a certain address belongs to them.
That means that the longer you go between scans, the more blocks you need to download and process.
With BIP47, as a receiver, you just need to look for notification trabsactions, it's orders of magnitude faster.
> The longer you go between scans, the more blocks you need to download and process
It's important to note that because of cutthrough (utxos that are already spent can be skipped), this statement isn't entirely true. If you wait long enough between scans, the data you need to process will approach a constant.
Yeah all I can say is try it really. It’s stupid simple. For some reason, I never was able to even test BIP-47. Not sure why SP got more traction than that