It certainly can be. At its core, the term basically means oen of three things:

1. We don't like you and we don't know why

Or

2. We don't like you and don't want to tell you why because the reason is against their law/might lead to a lawsuit.

Or finally:

3. We don't like you but want to sugar coat it a bit because we don't want to make you extremely annoyed/upset.

In some cases, that can really be a codeword for discrimination, since telling someone they're not hired because of their race/gender/age/nationality/whatever is against the law. But in other cases, it can often just be that the company has one way of working/prefers one environment and the candidate has another. If someone just doesn't get along with the people already at the company, well that's not necessarily discrimination if they don't get hired by that company.

So yeah, it depends really.