That’s coming from a properly liberal frame of reference (not just in the ‘invisibilising’ of socialism). Think the main problem with liberalism has always been its methodology - it’s always ahistorical, and necessarily so because to use a historical methodology is, firstly, a Marxist invention, and secondly a great way to expose the contradictions and hypocrisies of embedded liberalism. Instead it relies on things like ‘comparative analysis’, i.e. compartmentalising two phenomena (e.g. ‘the right’ and ‘the left’) and compartmentalising outcomes (‘successful’ and ‘not successful’) and trying to determine the cause of the outcome based on an analysis of current events (often quantitative data of something like… idk, how many people view x show when the topic is immigration vs when it’s about tax, or the voting patterns of people in scenarios where condition ‘x’ holds or whatever. Can’t be bothered to think of another example sorry).
Anyway ‘liberal’ views are diverse because liberalism is the politics of a kind of capitalism that recognises long-term profits are secured within a rights-based society (instead of fascism and… whatever the Tories are, which values short-term asset stripping and resource exhaustion over long-term profits), while socialism believes that a) a liberal rights based society is still barbaric, but mostly to the economic periphery, and b) it’s inherently unstable anyway and, without the strong presence of socialist agonism via the Trade Union movement and the existence of other left institutions, will always lead to authoritarianism. Liberalism is also not historically concerned with building any sort of united ‘movement’ because liberalism is already embedded in our political economy (although the people’s vote thing is the first sign of a movement of sorts in the UK).
I expect a lot of the division on the socialist left is historically as a result of interference from outside actors, including intelligence agencies, undercover cops etc. But that’s only possible when the movement is as small as it has been the past 3 or 4 decades.