The concept of class can be used in two ways.
Subjectively or objectively.
Most people on this thread are using it subjectively, and so as a concept it is useless.
However, without the information that can be obtained from the various socio-economic groups, parliament and its work would really struggle to make sensible decisions in areas such as education, health, pensions and in fact most of its work.
But it isn’t just governments who use this information, doctors, teachers, prison officers, police, military etc,etc all use it.
You can call these groups by any name you wish if class makes you feel queasy, but the information on which you base your political decisions will be the same.