I've figured that Sage was walking away from MAS 500 as soon I heard about X3, and watched their contortions justifying how it complements MAS 500. Even before that, I'd heard from technical analysts about how troublesome the code architecture in MAS 500 is. VB!!?? So, if they could find a polite way to walk away from it, they would.
SLX is, I think, more complicated. But I won't argue too hard with your conclusion. Sage CRM was added to Sage thru the ACCPAC acquisition. Some of SLX partners actually signed up for ""ACCPAC CRM"" before Sage bought it because of its web interface and single-tenant SaaS architecture which enabled hosted or on-prem installations. But feature-wise it was weak, and compared to SLX, it's UI was difficult. I know Sage at many levels struggled with how to deal with it vis-a-vis SLX. The big strike against SLX at the time was that it had no decent web interface.
But Dublin has done a great job of building out its features. It is now more than simply respectable, and because it has become the de facto integration CRM for all Sage ERP, it is here to stay.
Is there a decent case to make for 2 good CRM's in the Sage stable? Probably not. Too bad, because if there was ever a case for overspending on short-term R&D in order to get long-term payoff, it was the effort Scottsdale made to get the current web version out. It is very good, but it took too damn long, and possibly missed the window.
I also think @LouisAraiza is correct.