I mean, the data does seem to support a tech environment that applies disproportionate pressure on women to perform certain activities. From the linked HBS study, for example (Figure 6.1), 71% of women in tech feel pressure to put in face time (vs. 19% in all sectors) and 36% feel pressure to be available 24/7 (vs. 26% in all sectors).
Both of these are time-consuming activities. Myriad studies show child care responsibilities, even today, still fall disproportionately onto women. Child care is time-consuming, and that comes into conflict with time-consuming professional work.
Of course, not all women want children. And this is one study. But it wouldn't surprise me if women were underrepresented in tech due to a combination of cultural issues and the pipeline problem. It's just extremely reductionist when people assign blame to the pipeline problem, since that shifts the focus from work environments to higher education. That's a convenient result for companies.
I personally know people from underrepresented groups in tech (African-American, women etc) who attest that, even in work environments that made them feel 100% welcome/comfortable, they felt a mental cost from the very fact of being underrepresented. That is to say, even if you were to remove all the consciously and unconsciously biased behavior from workplaces, some people still have a negative reaction to being the only present member of a group that they identify with. The pipeline problem is the only solution that could possibly address that[1], by addressing the imbalance per se.
[1] I suppose short of having people stop feeling this way about being underrepresented. I've been underrepresented ethnically in almost every group I've ever been in, but it has never bothered me. Far be it from me to tell other to stop feeling a certain way though.