Question

why social marginalisation is not desirable

Answer 1

social marginalisation is a social disadvantage  to a part of the society. it is the process where a particular community or an individual is excluded from the society.
they are blocked from various rights, opportunities and resources that are available to the other communities or individuals. this marginalisation also applies to those who are disabled, minorities etc. the outcome of social marginalisation affects their social life in the community where they live.