The consequence is when media outlets and companies use this place as a guidance to what mothers and women think, and rarely put into consideration the differences in being a parent and woman that is not White. I can't recall the last survey in here that asked about my ethnicity and far too often I hear my ethnicity is not as important as other parts of my identity which is great when your ethnicity is rendered socially invisible by the current systems, but for many of us it is important to who we are in all facets of ourselves, not something that could be stripped off as is often requested.
The treatment of White as a universal perspective within the current systems where White is considered the normal position, rather than the reality of just being the most frequent within the UK (obviously not globally), has the consequence that everyone else's point of view is othered and seen as not real motherhood and not real perspectives as women as well as the frequent issue of White posters refusing to believe posters of other races because they do not experience the same issues. The issue is also expanded to campaigns - for example, the campaign about sexualization of girls focused on media and clothes, ignoring the fetishization that many girls experience is purely because of their race, have different rape rates because of their race.
It isn't just about demographics, it's about representation, philosophy, and actions. Recognising the issue means that these things can be considered - it likely wouldn't change a great deal for most but many little things could have taken consideration of - like when discussing the pay gap the statistics for different ethnicities could be included - maybe alongside many other gaps that are often ignored (disabilities, sexuality, and so much more). In discussing the overseas sex trade, it is often reduced to men as the problem when the vast majority are White men and in many areas White women as well but in very different ways (White men tend to do one night stands on holidays, White women tend to house underage youths in apartments). In discussions of violent acts, if done by a White person their race will basically never be seen as a considering factor while it pretty much always will when it done by anyone else. These things are noticed and could be noted as part of the general discussion.
No, we can't see the races of other people posting on the board, but we can see who gets represented, and whose perspectives are given the most time, whose race gets called up and whose are ignored and whose issues are and are not included. Hand waving it off simply means supporting a system where the White perspective is still held up as the standard to hold others up to rather than just the most frequent within the UK alongside other equals.