Every slot you have can hold an enchantment. I had a set of Amber armour, all enchanted with 20% chameleon. Five x 20 is 100, I was invisible at all times.
Less slots mean less to enchant which means less to abuse.
abuse: To use wrongly or improperly
They let it happen for at least to games so it was not wrong or improper
They are removing it now because just like in da2 (removal of companion armor) and Me2 (removal of all loot) people dont want choices, they want pow awesomeness, not looking at 8 armor pieces and actually determining what would make their character better.
They cant say its about what is shown when other companies are doing the same exact thing and are actually telling the truth about it