I find the way factions are talked about in RPGs a bit odd. In normal usage, a faction is a small, dissenting group. Sometimes, the hobby does use the term this way. The problem is when every and any social group is described as a faction. The peasantry for example, hardly seem to fit the bill.
Perhaps it’s just that “faction” has a wider application in RPGs than normal usage. By the term, people really just mean a social group, applicable to both a band of mercenaries and a global empire (as in this post). The issue then becomes one of oversimplification, when you end up treating every social group the same way.
For me, this isn’t just semantics because I find that a genuinely factional setting makes for interesting gameplay. But I’ve come to realise, despite the hobby’s talk of faction play, that many old school adventures don’t actually contain that many factions. To explain this requires a bit more clarity about what I think counts as a faction.