The general evidence for washing hands as an effective counter-measure is very very strong. It is a complete no-brainer, while decisions regarding face masks are complex and have to take into account lots of variables.
I think you misread me, I meant "general" as in general counter-measure, not COVID19-specific. Clearly I should have been more precise. In a situation where overload of healthcare is a primary concern, recommending counter-measures against general infections (where hand hygiene qualifies) is a no-brainer.
Meta-studies show that the effectiveness of hand washing alone is minimal https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4891197/