Calling things addictions is a way of stigmatising socially disapproved-of things. Addiction is about "dependency" and "need". For socially approved-of activities, the exact same psychological state would be called "interest", "dedication", "commitment", "expertise", "professionalism" or "enjoyment".
The same psychological state -- liking something a lot and using it all the time -- has both very positive and very negative words. Which is used depends on the values of the speaker, or the authority of cultural traditions, rather than the user. So it's dehumanizing -- it's a subtle way to deny his life should be run by his own values.
The idea of addictions is also a medicalization of ethics. It tries to turn an issue of ethics -- judging lifestyles as good or bad -- into one of medical science with no ethical judgment needed. We have a word for that: scientism.
The only morally sustainable distinction in this area is that between activities that *the person concerned* finds pleasant and/or useful, and those that he himself finds unpleasant and useless but cannot help repeating. When the addict does not want to be an addict is the only time addiction is a legitimate term. Whenever its used because the speaker wants someone to change his lifestyle he's just an authoritarian masking his moral judgments behind a false veneer of science.