Having worked with Salesforce deployments over the last two years. I'd only call it malleable as long as you fit in its definition of what's malleable. I'm half-expecting it to have its own definition of a wheel at this point.
I think there are other systems that kinda get there but SFDC is the only one of these kinds of systems that give you a lot of options on the backend and frontend side of things to just ship your own things and have them be integrated.
As for your specific question, I'll be honest, I'm not familiar enough with what the competition has to offer, because I tend to avoid these behemoth monolithic locked-in platforms like the plague if I can help it, and my experience with Salesforce so far isn't really making it easy for me to change my mind on the subject.