How come 5-year-old pony art never took off?

[Never2muchpinkie 208]

Given what I've seen of this fandom there is a huge amount of fanart for basically EVERYTHING!  Twilicane. background ponies, you name it, there is probably at least 100 pictures of it.  However, despite 5 year old Sweetie Belle being a big deal in "For whom the Sweetie Belle toils" there is barely any fan art of what was finally the 5th stage of pony development show in the show apart from baby, foal, adult, and elderly. 

 

Nearly all the pictures shown for it come directly from the show. So what was it about this that made it pick up no interest or attention?

[Jeric 46,835]

If you go though the Rarity Fan Club you'll run into more than a few pieces of a younger sweetie belle

 

[Never2muchpinkie 208]

If you go though the Rarity Fan Club you'll run into more than a few pieces of a younger sweetie belle

 

I'm sure there is, but I was talking about other ponies, like the mane 6 or even the other 2 crusaders.  I just don't know why it never made the fanart rounds considering that basically everything else gets tons of love in the fandom.