Some United fans are disseminating a video of Graeme Souness wherein he is illustrating indiscipline and they are using this video to conclude that he was a bad player in some way. Rather, Souness was an excellent player in his time and that isn't debatable.

I could easily put together a similar video of Roy Keane, Paul Scholes, Sergio Ramos or Gennaro Gattuso and arrive at the same conclusion if I am basing my viewpoint on bias. Do not allow Souness’ petulant antics distract you from rational analysis.

Likewise, other accounts are attempting to counteract these fans but they are conveying extreme opinions on the other side by saying Souness was “comfortably” or “significantly” better than Pogba and this is a fallacy in multiple ways.

Something to mention:

Souness loves to speak about Pogba's “lack of discipline” whilst he, himself, was one of the most indisciplined players in his time and arguably all time. This was known at the time and was a consistent feature of discussion especially in the early 80s.

Overall, it is expected that fans would resort to this sort of thing but do not allow yourself to be caught up in it. Be rational and logical in your analysis of players regardless of their antics. It can be difficult, yes, but that is what the sincere and truthful person does.