It appears that a number of people dislike the categorization of STEM into hard and soft STEM and I understand their reasons. Additionally, if I were a guy, there is an obvious reason why I would never want to be known as "soft." But it seems people dislike being categorized altogether.
I think we all like to think we are unique, snowflake-like researchers who totally escape all categorization. We bridge multiple fields, we do a little bit of this and a little bit of that, all in our own unique way. There is no chance that there is anyone quite as awesome, versatile, and interdisciplinary as we are, right? But, alas, who can ever really evaluate us in all our unique interdisciplinary glory?
Let's try the following scenario: You are up for tenure. Your department colleagues want to promote you. But, there is usually at least one additional step, where a committee composed of members of different departments is supposed to evaluate your case and often this is who really decides your destiny. These committees usually have different department compositions in different years. Bear in mind that a representative of your department cannot vote (even if there is one on the committee) and neither can any of your close collaborators that happen to be on the committee.
So, which departments are likely to yield a representative that will be able to adequately assess your tenure dossier? In particular, which department's representatives will be most appreciative of the research metrics such as your publication record (e.g. publication quality, publication rate, relevant journals) and your funding record, without entirely relying on the information in the external evaluation letters? If you comment on this, please state what your field is and list 3-5 such departments, whose representatives are likely to fully appreciate your awesome record and if necessary be able to champion your case to the rest of the committee.
If thoughts of a tenure decision leave you drenched in sweat (e.g. because you don't want to live through it again or because it's coming up soon), you can consider a similar scenario where you are up for an Excellence in Research university award, as to be determined by a committee of 5 people. Which 3-5 departments are those whose representatives you woul ideally want on the committee to ensure full appreciation of your research awesomeness?
While each of us may well be a unique, snowflake-like researcher who totally escapes all categorization, it's not a bad idea to sometimes think which other fields we can easily (or not so easily) make a bridge to. This is important when we are evaluated for tenure and promotion, when we seek new funding, when we think of new research directions, when we start collaborations. (Or when someone on the internet invites us to take a poll about where our discipline belongs.) Sometimes the best new research directions come precisely from realizing that another field is sufficiently different from ours that some well-known techniques from our field may enable some very exciting breakthroughs in the other field.
Different categorizations emphasize different common aspects, no more and no less: with some fields we share the same scientific journals and/or the sources of funding; with some others we may share the same poor representation of women or minorities among faculty and students; with many more we get grouped into colleges and schools, according to tradition, or politics, or disciplinary similarities. Finally, there are many aspects all academics share, such as our teaching and service missions, and that's why we are all grouped into universities.