This is simply journalese, where omitting words when the meaning can still be grasped is common. In fact what the question quotes is a headline, where this tendency is even more marked. Much the same phrase appe3ars in the body of the article:
Remainers, passionate pro-Europeans, sensible pragmatists, people who over a lifetime have earned a measure of respect across parliament, tear off their clothes of respectability to abase themselves in pursuit of ... what? A job? Influence?
It is not absolutely clear if this is a list of four groups: remainers, pro-europeans, pragmatists, and "people who .. have earned ... " or if only the first three groups are intended, with the "people who" phrase a description of all three. The sense is not very different in either case. But that sows why using an 'and" here would indeed have been better writing -- it would have avoided the ambiguity