I used to be a keen socialist, from age about 13-18 - and as a teen I read fairly widely in the British tradition: William Morris (very much liked him), The Fabians (GB Shaw, Wells etc), Tawney (Christian socialism) and modern people like Schumacher, Anthony Crosland, modern Fabian Essays, the New Statesman every week...
(I was never a Marxist, however.)
Socialism is of course egalitarian, that is it is focused on equality - and most of the early socialists wanted equality of opportunity - an essentially equal chance for everybody, but naturally leading to unequal economic outcomes.
(The recognized the obvious truth that strictly equal opportunites lead to unequal outcomes.)
They focused on levelling-up of economic conditions, and on education: compulsory education for all, more schools and colleges, more scholarships for the poor, better schools all round etc.
George Bernard Shaw regarded this as insufficient, and argued for economic equality - specifically equal salaries for all - he regarded this as sufficient to address the problems of inequality - but of course he allowed for many other differences.
Essentially Shaw wanted to settle the economic problem (and socialism was based on an economic analysis) - and allow people to get-on with more important matters.
But none of these early socialists argued that people were equal.
None argued that that individuals and groups were the same.
They did not argue same-ness because it obviously was not true - to argue to would have been simply insane, nobody would have taken them seriously at all.
And because people were not the same, therefore their outcomes in a system of equality would naturally be different. Therefore if (like GB Shaw) you wanted equal outcomes you had to impose them coercively - precisely because people were not the same, and if you did not coercively-impose equal outcomes you would not get them.
They realized that as soon as you stopped actively-imposing equal outcomes, then outcomes would again become unequal.
Yet nowadays same-ness of all people and groups is precisely the default of Leftism - and the assertion that because all people and groups are the same, then and difference in outcomes must have been coercively imposed.
Now, this modern doctrine of the same-ness of people and groups is not just a stupid and indefensible error - because it is not the kind of thing that somebody can be wrong about, it is not the kind of thing that could possibly be the result of a mistake.
None of the early socialists believed it, perhaps nobody believed it until the mid-twentieth century - and it was not believed then as the result of any kind of discovery!
So, the modern near-universal belief in the same-ness of people is not, therefore, any kind of stupidity, nor is it due to any kind of un-informedness.
And, although this belief is obviously insane - it is not plausible to imagine that belief in the same-ness of people was caused by actual clinical mental illness affecting the intellectual elite en masse...
No, no - what a belief in the same-ness of people is, is evil; pure evil.
(Evil is the destruction of Good - and Good is truth, beauty and virtue - in unity.)
Belief in the same-ness of people is an ideology which allows un-bounded destruction of human society - at every level - and without limit or restraint - and continuing until there is nothing left that can continue the process of destruction.
This is not the kind of thing that happens by accident, or as a consequence of well-meaning people blundering in their analysis and actions - it is done by people in service to pure evil.
The people themselves may or may not be evil or nasty people - just as Maoist Commisars, Gulag guards and Gestapo may or may not have been evil or nasty people.
But those who believe in the same-enss of humans serve evil - they are on the side of evil - and this is a straightforward objective fact: anyone who believes-in, argues for, or enforces policy based-on the same-ness of people and groups is serving evil.