It's a good point you brought up. It is a point I thought about at the time of writing that article.
I do not mean that a person who plays with their toys is not a collector. A collector can surely play with his/her toys.
What I mean is that I do not consider the toys that were given to me when I was young "collecting". Thinking back, they were just toys. Toys that were given to me. I did not "collect" them, I simply had them.
A kid may have a "collection" of toys, but that does not mean that the kid is collecting or a collector. A person is not a collector simply by having a "collection" of something in his/her possession. To be collecting, a person must consciously turn his/her mind to the act of collecting and be conciously seeking more and/or having particular milestones or objectives for the collection.
This might be something you have turned your mind to at a young age, but I certainly did not.
In short, collecting is a conscious decision and should be something more than just "sitting" on an assortment of figures that were given to the person.