I can answer this openly: basically there are at least 3 reasons.

First, the concepts relating to the skills

are understood but not their application.

Concepts and application are 2 diffetent things.

Second, the soft slills learnt cannot be applied because the organization has a very different culture. For example, the culture is top-down so skills relating to empowerment cannot flourish.

Third, there are no incentives to use sills learnt, so employees just keep the skills to themselves or maybe just aplly it selectively with just 2-3 close colleagues.

Fourth, rank in organization is also a factor. Higher level managers can apply skills more essily than lower level managers.

Fifth, cultural reasons. Certain skills are more easily applied in certain cultures. This, delegation skills are easier to apply in cultures that emphasize egalitarian values than cultures that are hierarchical.

There are also many issues around how these 'soft skills' are taught. We see this a lot in the youth development/sport literature around the analogous concept of 'life skills'.

There needs to be a clear (cognitive) connection between the skills taught and their potential application in 'outside' settings. And individuals need to be given opportunities to practice those skills in meaningful situations. Learning them in a workshop or sport session are only a start.

Though Teddy Lian is right to mention many of the external/environmental pressures that influence use of 'skills', the structure and delivery of that skills education is also quite important.

Some useful literature from the sport field exists, including from Corliss Bean or Martin Camiré, that might be worth checking out.