This is how I see the issue..
Most people have (albeit minor) OCD-like quirks; that person who has to have things perfectly straight, or touch things, or have things a certain way.
These things can be exacerbated by situation - my first example is that I have had severe sleeping problems that only ended about two years ago. My brain's defence against that around the 15-16 mark was for me to have to have multiple things perfect around the room. I would take time each night to arrange each object, and if it didn't go perfect, I would move it until it did (my longest was over 20 minutes arranging a dressing gown).
My second is my borderline PD friend - her brain's defence is to make her tap each doorway twice as she goes through (as well as some other things), which is just as vitally necessary for her as my bedroom-arranging was.
Neither of us have ever said "I'm a bit OCD", ever. They are OCD-style traits, but nowhere near the maladaptiveness and difficulty of the time-consuming nature that an OCD sufferer has. They are minor traits that have been exacerbated by another issue, but not enough so to legitimise calling it OCD.
I know that it's just a turn of phrase. But it does trivialise the disorder. This is because everyone knows the difference between "I'm starving" and someone actually starving, but there is too much misinformation about mental disorders. That's why people can say "I'm depressed", then turn to someone who actually suffers from depression and say "hey, we all have problems, I've managed to cheer up so why can't you?"
Both me and my friend have mental disorders, and I think that is why we are more sensitive to this particular issue.