I think the difference is that I like to see what people are like as people before I interview. I can give someone skills, I can't give them a personality.
That is true, people can learn, I actually rarely look for skills but look for intelligence, ability to learn, ability adapt, and a strong will to learn etc.
If someone has a relevant skill or experience then that is a bonus, may save time in training and may be an indicator that they have a natural ability for that task. I help hire software developers and we mainly look at math and physics candidates with a PhD often without any programming experience, we will test their problem solving ability and analyse how their thinking process works to see if they are a good fit. If hired they can learn software development relatively quickly.
Personality is very important and is one of the key reasons why you interview people. I don't know about you but I cannot judge someone's personality from only a few words they have written on a CV. I will chat for them for an hour over lunch or dinner to see if they would fit.
Putting interests on a CV can also lead to problems of they are not carefully chosen. E.g., "socialising with friends" may be interpreted as going out and getting drunk, turning up for work either hungover or simply not with a fresh mind - older managers may not appreciate such statements (especially hings like "clubbing". Even things like saying you take a sport very serious entering competitions may be frowned upon because it often means you are away training and taking part in competitions, yet it could be taken very positively showing commitment and determination.
I have also seen people state thinks like "Karate", having down some TKD in the past I asked them about their martial arts and it turns out he only went to a few lessons but loves watching kung fu movies.
On the flip side if you can have interests that are supportive of the job role it can be very positive, e.g. applying for a web developer and you say you help design webpages for charities in your spare time would be a big positive.
This is a bi long but my point is I cannot judge someone's personality by a few words at the bottom of a CV, hence they have no relevance. Space on a CV is t a premium, even without adding more text you just use the space saved to spread out your CV and make it look less cluttered is a very positive thing.