Because society just like to label things as crazy or weird that don't meet there standards...if they found out sociopaths could love and everyone is okay with it then i gaurantee we would be "normal" in societies eyes. Thisnis why i hate "normal" people...
If I can emulate all the other bullshit people do, why the fuck would love be different? Anyone saying a sociopath can't love just got tricked into believing she (most likely) was loved and then got taken advantage of. Just because it happens doesn't mean it happens to every relationship with a sociopath.
Anyways,
Its hard to say if a sociopath can experience love, without actually defining it.
Under some definitions it would be impossible. I think some people would actually be incapable. But most people, even AsPD, NPD, BPD, Psychopaths, etc, are capable of experiencing an attachment to someone to an extend that can be considered at least borderline love. However whether thats enough for the other partner, that is different. It also depends on how you manifest said attachment.
The way i understand it, love is connected to giving a fuck about the other person and ignoring what you want, to a reasonable extend, to make the other feel good. Most PD's have a problem with reason, so you can see how this will fail.