In short
Four things the evidence supports
Clinical skills are assessed. Practice is not.
Qualification programmes are designed and examined around clinical competence, and rightly so. The capabilities that determine whether a graduate still has a practice in three years, becoming findable, converting enquiries, setting prices, managing a caseload and protecting their own capacity, sit largely outside what is taught and almost entirely outside what is assessed.
The failure point is capability, not effort.
The micro-enterprise literature consistently locates survival and growth in human and social capital rather than in hours worked. Solo practitioners are typically working hard. What is missing is a structured set of non-clinical competencies and the conditions to practise them.
Solo practice concentrates demand and removes the buffers.
Job Demands-Resources and emotional-labour research describes what happens when high emotional demand meets low organisational resource. A salaried clinician has colleagues, supervision, admin support and a fixed income. A sole practitioner has none of these, and carries the commercial risk as well.
Information does not close it. Practice does.
The gap is behavioural, not informational. Transfer-of-learning research is clear that capability develops through authentic tasks in the learner's own setting, with timely feedback and iteration, not through content delivered once. This is why business webinars rarely change anything.
The research underpinning these statements is set out in full, with 87 cited sources across five disciplines, on the evidence base page.