Can the use of the Mental Health Act be the 'least restrictive' approach for psychiatric in-patients?

In England and Wales, involuntary admissions for assessment or treatment in mental health wards are based on the legal framework of the Mental Health Act 1983 (as amended in 2007) or the Mental Capacity Act 2005, with the Deprivation of Liberty Safeguards introduced in 2007. But what is the "least restrictive" approach and are we truly safeguarding in-patients’ liberty by curbing use of the Mental Health Act in particular groups