update Compatibility section

Author: hugohn

bip-hugonguyen-bsms.mediawiki

@@ -185,7 +185,9 @@ For signers that use QR codes to transmit data, key and descriptor records can b
 Also refer to [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-015-account.md UR Type Definition for BIP44 Accounts] and [https://github.com/BlockchainCommons/Research/blob/master/papers/bcr-2020-010-output-desc.md UR Type Definition for Bitcoin Output Descriptors] for more details.
 
 ==Compatibility==
-BSMS is opt-in, meaning existing multisig wallets can continue working as-is, with the caveat that current multisig solutions are full of pitfalls. Some of the problems have been described in the [[#Motivation]] section.
+This specification is not backwards compatible with existing multisig implementations.
+
+BSMS is opt-in, meaning existing multisig implementations can continue working as-is, with the caveat that they are full of pitfalls. Some of the problems have been described in the [[#Motivation]] section.
 
 To comply with this standard, a Signer must be able to persist the descriptor record in its storage.